merge revision(s) 44195: [Backport #7772]

	* util.c (ruby_qsort): fix potential stack overflow on a large
	  machine.  based on the patch by Conrad Irwin <conrad.irwin AT
	  gmail.com> at [ruby-core:51816].  [Bug #7772]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@44565 b2dd03c8-39d4-4d8f-98ff-823fe69b080e