merge revision(s) r46796: [Backport #10008]

	* configure.in (rb_cv_broken_backtrace): exit with failure
	  normally, no needs to abort.  [ruby-core:63678] [Bug #10008]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@47418 b2dd03c8-39d4-4d8f-98ff-823fe69b080e