merge revision(s) 40276: [Backport #8210]

	* Merge Onigmo 5.13.4 f22cf2e566712cace60d17f84d63119d7c5764ee.
	  [bug] fix problem with optimization of \z (Issue #16) [Bug #8210]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@40384 b2dd03c8-39d4-4d8f-98ff-823fe69b080e