merge revision(s) 41777,41779: [Backport #8593]

	* lib/mkmf.rb (have_framework): allow header file to check.
	  [ruby-core:55745] [Bug #8593]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@42357 b2dd03c8-39d4-4d8f-98ff-823fe69b080e