railsでnio4rがbundle install出来ない

OSX EL Capitan(10.11.1)にて

```
Installing nio4r 1.0.0 with native extensions

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    /Users/shwld/.rbenv/versions/2.1.5/bin/ruby extconf.rb
checking for rb_thread_blocking_region()... yes
checking for sys/select.h... yes
checking for poll.h... yes
checking for sys/epoll.h... no
checking for sys/event.h... yes
checking for sys/queue.h... yes
checking for port.h... no
checking for sys/resource.h... yes
creating Makefile

make "DESTDIR=" clean

make "DESTDIR="
compiling monitor.c
In file included from monitor.c:6:
In file included from ./nio4r.h:10:
/Users/shwld/.rbenv/versions/2.1.5/include/ruby-2.1.0/ruby/backward/rubyio.h:2:2: warning: use "ruby/io.h" instead of "rubyio.h" [-W#warnings]
#warning use "ruby/io.h" instead of "rubyio.h"
 ^
1 warning generated.
compiling nio4r_ext.c
In file included from nio4r_ext.c:6:
In file included from ./nio4r.h:10:
/Users/shwld/.rbenv/versions/2.1.5/include/ruby-2.1.0/ruby/backward/rubyio.h:2:2: warning: use "ruby/io.h" instead of "rubyio.h" [-W#warnings]
#warning use "ruby/io.h" instead of "rubyio.h"
 ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:481:48: warning: '/*' within block comment [-Wcomment]
/*#define MIN_INTERVAL  0.00000095367431640625 /* 1/2**20, good till 2200 */
                                               ^
./../libev/ev.c:974:42: error: '_Noreturn' keyword must precede function declarator
  ecb_inline void ecb_unreachable (void) ecb_noreturn;
                                         ^~~~~~~~~~~~
  _Noreturn
./../libev/ev.c:777:26: note: expanded from macro 'ecb_noreturn'
  #define ecb_noreturn   _Noreturn
                         ^
./../libev/ev.c:1535:31: warning: 'extern' variable has an initializer [-Wextern-initializer]
  EV_API_DECL struct ev_loop *ev_default_loop_ptr = 0; /* needs to be initialised to make it a definition despite extern */
                              ^
In file included from nio4r_ext.c:7:
In file included from ./../libev/ev.c:2400:
./../libev/ev_poll.c:110:18: warning: expression result unused [-Wunused-value]
        assert (("libev: poll() returned illegal result, broken BSD kernel?", p < polls + pollcnt));
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2806:12: warning: expression result unused [-Wunused-value]
  assert (("libev: watcher has invalid priority", ABSPRI (w) >= 0 && ABSPRI (w) < NUMPRI));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2809:14: warning: expression result unused [-Wunused-value]
    assert (("libev: pending watcher not on pending queue", pendings [ABSPRI (w)][w->pending - 1].w == w));
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2819:16: warning: expression result unused [-Wunused-value]
      assert (("libev: active index mismatch in heap", ev_active (ANHE_w (heap [i])) == i));
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2820:16: warning: expression result unused [-Wunused-value]
      assert (("libev: heap condition violated", i == HEAP0 || ANHE_at (heap [HPARENT (i)]) <= ANHE_at (heap [i])));
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2821:16: warning: expression result unused [-Wunused-value]
      assert (("libev: heap at cache mismatch", ANHE_at (heap [i]) == ev_at (ANHE_w (heap [i]))));
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2832:16: warning: expression result unused [-Wunused-value]
      assert (("libev: active index mismatch", ev_active (ws [cnt]) == cnt + 1));
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2850:14: warning: expression result unused [-Wunused-value]
    assert (("libev: negative fd in fdchanges", fdchanges [i] >= 0));
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2863:24: warning: expression result unused [-Wunused-value]
              assert (("libev: io watcher list contains a loop", w != w2));
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2867:20: warning: expression result unused [-Wunused-value]
          assert (("libev: inactive fd watcher on anfd list", ev_active (w) == 1));
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:2868:20: warning: expression result unused [-Wunused-value]
          assert (("libev: fd mismatch between watcher and anfd", ((ev_io *)w)->fd == i));
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3050:24: warning: expression result unused [-Wunused-value]
              assert (("libev: negative ev_timer repeat value found while processing timers", w->repeat > 0.));
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3112:24: warning: expression result unused [-Wunused-value]
              assert (("libev: ev_periodic reschedule callback returned time in the past", ev_at (w) >= ev_rt_now));
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3274:12: warning: expression result unused [-Wunused-value]
  assert (("libev: ev_loop recursion during release detected", loop_done != EVBREAK_RECURSE));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3431:9: warning: 'rb_thread_blocking_region' is deprecated [-Wdeprecated-declarations]
        rb_thread_blocking_region(ev_backend_poll, (void *)&poll_args, RUBY_UBF_IO, 0);
        ^
/Users/shwld/.rbenv/versions/2.1.5/include/ruby-2.1.0/ruby/intern.h:870:18: note: 'rb_thread_blocking_region' has been explicitly marked deprecated here
DEPRECATED(VALUE rb_thread_blocking_region(rb_blocking_function_t *func, void *data1,
                 ^
/Users/shwld/.rbenv/versions/2.1.5/include/ruby-2.1.0/x86_64-darwin15.0/ruby/config.h:114:52: note: expanded from macro 'DEPRECATED'
#define DEPRECATED(x) __attribute__ ((deprecated)) x
                                                   ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3446:22: warning: expression result unused [-Wunused-value]
            assert (("libev: pipe_w not active, but pipe not written", ev_is_active (&pipe_w)));
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3620:12: warning: expression result unused [-Wunused-value]
  assert (("libev: ev_io_start called with negative fd", fd >= 0));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3621:12: warning: expression result unused [-Wunused-value]
  assert (("libev: ev_io_start called with illegal event mask", !(w->events & ~(EV__IOFDSET | EV_READ | EV_WRITE))));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3630:12: warning: expression result unused [-Wunused-value]
  assert (("libev: ev_io_start called with corrupted watcher", ((WL)w)->next != (WL)w));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3632:34: warning: '&' within '|' [-Wbitwise-op-parentheses]
  fd_change (EV_A_ fd, w->events & EV__IOFDSET | EV_ANFD_REIFY);
                       ~~~~~~~~~~^~~~~~~~~~~~~ ~
./../libev/ev.c:3632:34: note: place parentheses around the '&' expression to silence this warning
  fd_change (EV_A_ fd, w->events & EV__IOFDSET | EV_ANFD_REIFY);
                                 ^
                       (                      )
./../libev/ev.c:3645:12: warning: expression result unused [-Wunused-value]
  assert (("libev: ev_io_stop called with illegal fd (must stay constant after start!)", w->fd >= 0 && w->fd < anfdmax));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3665:12: warning: expression result unused [-Wunused-value]
  assert (("libev: ev_timer_start called with negative timer repeat value", w->repeat >= 0.));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3693:14: warning: expression result unused [-Wunused-value]
    assert (("libev: internal timer heap corruption", ANHE_w (timers [active]) == (WT)w));
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3755:16: warning: expression result unused [-Wunused-value]
      assert (("libev: ev_periodic_start called with negative interval value", w->interval >= 0.));
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3787:14: warning: expression result unused [-Wunused-value]
    assert (("libev: internal periodic heap corruption", ANHE_w (periodics [active]) == (WT)w));
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3824:12: warning: expression result unused [-Wunused-value]
  assert (("libev: ev_signal_start called with illegal signal number", w->signum > 0 && w->signum < EV_NSIG));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3827:12: warning: expression result unused [-Wunused-value]
  assert (("libev: a signal must not be attached to two different loops",
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:3945:12: warning: expression result unused [-Wunused-value]
  assert (("libev: child watchers are only supported in the default loop", loop == ev_default_loop_ptr));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
In file included from nio4r_ext.c:7:
./../libev/ev.c:4524:14: warning: expression result unused [-Wunused-value]
    assert (("libev: loop to be embedded is not embeddable", backend & ev_embeddable_backends ()));
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/assert.h:93:25: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                        ^
32 warnings and 1 error generated.
make: *** [nio4r_ext.o] Error 1

make failed, exit code 2
```

ver1.1で解決しているらしいので、以下のコマンドを実行した
```
bundle update nio4r
```