merge revision(s) 40216: [Backport #8266]

	* ext/fiddle/closure.c (initialize): check mprotect's return value.
	  If mprotect is failed because of PaX or something, its function call
	  will cause SEGV.
	  http://c5664.rubyci.org/~chkbuild/ruby-trunk/log/20130401T210301Z.diff.html.gz


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@40290 b2dd03c8-39d4-4d8f-98ff-823fe69b080e