Ruby

dir.c: use rb_gc_for_fd

• dir.c (rb_dir_s_empty_p): use rb_gc_for_fd for the condition to
  invoke GC by errno.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56466 b2dd03c8-39d4-4d8f-98ff-823fe69b080e