merge revision(s) 41764,41765,41767: [Backport #8583]

	* regcomp.c (): Merge Onigmo 5.13.5 23b523076d6f1161.
	  https://bugs.ruby-lang.org/issues/8583
	  * [bug]  (thanks Akinori MUSHA and Ippei Obayashi)
	           Fix a renumbering bug in condition regexp with a named
	           capture. [Bug #8583]
	  * [spec] (thanks Akinori MUSHA)
	    Allow ENCLOSE_OPTION in look-behind.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@41780 b2dd03c8-39d4-4d8f-98ff-823fe69b080e