* io.c: fix issues in the last two commits. don't disable cloexec for
  platforms other than NativeClient.
* ChangeLog: ditto. add entries for the last two commits.
Sat Oct 11 11:12:00 2014  Yuki Yugui Sonoda  <yugui@yugui.jp>

	* signal.c (install_signalhandler, init_sigchld): allow failure because it
	  always fails with ENOSYS on NaCl.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47874 b2dd03c8-39d4-4d8f-98ff-823fe69b080e