* configure.in (_FORTIFY_SOURCE): added a few comments.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39771 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* configure.in: check struct timeval exist or not.
* include/ruby/missing.h (struct timeval): check HAVE_STRUCT_TIMEVAL
  properly. and don't include sys/time.h if struct timeval exist.

* file.c: include sys/time.h explicitly.
* random.c: ditto.
* thread_pthread.c: ditto.
* time.c: ditto.
* ext/date/date_strftime.c: ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39772 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* include/ruby/missing.h (struct timespec): include <sys/time.h>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39773 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* include/ruby/missing.h (__syscall): moved to...
* io.c: here. because __syscall() is only used from io.c.

* include/ruby/missing.h: move "#include <sys/type.h>" to ....
* include/ruby/intern.h: here. because it was introduced for
  fixing NFDBITS issue. [ruby-core:05179].

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39774 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* thread.c: disabled _FORTIFY_SOURCE for avoid to hit glibc bug.
  [Bug #8080] [ruby-core:53349]
* test/ruby/test_io.rb (TestIO#test_io_select_with_many_files):
  test for the above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39775 b2dd03c8-39d4-4d8f-98ff-823fe69b080e