glib2: fix infinite loop on Ruby 2.1 and 2.2

Use
rb_thread_call_without_gvl() instead of
rb_thread_call_without_gvl2(). rb_thread_call_without_gvl2() doesn't
run other threads. It's not expected expected
feature. rb_thread_call_without_gvl() may run other threads. It is
expected.

rb_thread_call_without_gvl2() has infinite loop problem with thread. For
example, the following code reproduces this problem:

    require 'gtk2'

    window = Gtk::Window.new
    window.show_all

    Thread.new do
      sleep
    end

    Gtk.main

Note: This problem is sometimes not happened.

Here are backtraces when the problem is reproduced. "Thread 1" is the
infinite looped thread. It seems that infinite loop is occurred in X.

    Thread 3 (Thread 0x7fffee90c700 (LWP 20748)):
    #0  pthread_cond_wait@@GLIBC_2.3.2 ()
        at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
    #1  0x00007ffff7aef689 in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #2  0x00007ffff7af025b in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #3  0x00007ffff7af082d in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #4  0x00007ffff7af26cf in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #5  0x00007ffff7af2d10 in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #6  0x00007ffff774b0a4 in start_thread (arg=0x7fffee90c700)
        at pthread_create.c:309
    #7  0x00007ffff6ac0cbd in clone ()
        at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

    Thread 2 (Thread 0x7ffff7ff5700 (LWP 20747)):
    #0  0x00007ffff6ab817d in poll () at ../sysdeps/unix/syscall-template.S:81
    #1  0x00007ffff7af5e48 in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #2  0x00007ffff774b0a4 in start_thread (arg=0x7ffff7ff5700)
        at pthread_create.c:309
    #3  0x00007ffff6ac0cbd in clone ()
        at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

    Thread 1 (Thread 0x7ffff7fc5700 (LWP 20732)):
    #0  0x00007ffff7751e9d in recvmsg () at ../sysdeps/unix/syscall-template.S:81
    #1  0x00007ffff393f077 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
    #2  0x00007ffff393f858 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
    #3  0x00007ffff34289c8 in poll_for_event (dpy=dpy@entry=0x19fc1b0)
        at ../../src/xcb_io.c:257
    #4  0x00007ffff3428b2b in poll_for_response (dpy=dpy@entry=0x19fc1b0)
        at ../../src/xcb_io.c:289
    #5  0x00007ffff3428e3d in _XEventsQueued (dpy=dpy@entry=0x19fc1b0,
        mode=mode@entry=2) at ../../src/xcb_io.c:363
    #6  0x00007ffff341a777 in XPending (dpy=0x19fc1b0) at ../../src/Pending.c:55
    #7  0x00007fffefca9ade in gdk_check_xpending (display=0x1a0d000)
        at /build/gtk+2.0-Gthrko/gtk+2.0-2.24.25/gdk/x11/gdkevents-x11.c:159
    #8  gdk_event_prepare (source=<optimized out>, timeout=<optimized out>)
        at /build/gtk+2.0-Gthrko/gtk+2.0-2.24.25/gdk/x11/gdkevents-x11.c:2361
    #9  0x00007ffff595746d in g_main_context_prepare ()
       from /lib/x86_64-linux-gnu/libglib-2.0.so.0
    #10 0x00007ffff5957e0b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
    #11 0x00007ffff5958272 in g_main_loop_run ()
       from /lib/x86_64-linux-gnu/libglib-2.0.so.0
    #12 0x00007ffff00374b7 in IA__gtk_main ()
        at /build/gtk+2.0-Gthrko/gtk+2.0-2.24.25/gtk/gtkmain.c:1257
    #13 0x00007ffff059dfe6 in rg_m_main (self=16405280) at rbgtk.c:226
    #14 0x00007ffff7ad4d56 in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #15 0x00007ffff7ae541d in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #16 0x00007ffff7addb83 in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #17 0x00007ffff7ae344d in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #18 0x00007ffff7ae514f in rb_iseq_eval_main ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #19 0x00007ffff79d0baf in ?? ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #20 0x00007ffff79d254d in ruby_exec_node ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #21 0x00007ffff79d426e in ruby_run_node ()
       from /usr/lib/x86_64-linux-gnu/libruby-2.1.so.2.1
    #22 0x00000000004008ab in ?? ()
    #23 0x00007ffff69fcb45 in __libc_start_main (main=0x400860, argc=32,
        argv=0x7fffffffe1b8, init=<optimized out>, fini=<optimized out>,
        rtld_fini=<optimized out>, stack_end=0x7fffffffe1a8) at libc-start.c:287
    #24 0x00000000004008d9 in _start ()

rb_thread_call_without_gvl2() is used since
c92a046cfe266cedbd59a40b31cfc9ea6e8ab300

[ruby-gnome2-devel-ja]

Reported by toshia. Thanks!!!