* thread.c (rb_thread_fd_close): unintentionally removed at r58094.

rb_thread_fd_close is unintentionally removed in 2.3.4.
Related commits are r57948,r57949,r57950 in trunk.
To remove ABI change, forward-port the recovery commit in ruby_2_2.

https://twitter.com/nalsh/status/851061221285445632

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@58141 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Author: unak

thread.c

@@ -2187,6 +2187,12 @@ rb_notify_fd_close(int fd)
     return busy;
 }
 
+void
+rb_thread_fd_close(int fd)
+{
+    while (rb_notify_fd_close(fd));
+}
+
 /*
  *  call-seq:
  *     thr.raise