merge revision(s) 43208: [Backport #9003]

	* compar.c (cmp_eq): fail if recursion.  [ruby-core:57736] [Bug #9003]

	* thread.c (rb_exec_recursive_paired_outer): new function which is
	  combinnation of paired and outer variants.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@43230 b2dd03c8-39d4-4d8f-98ff-823fe69b080e