merge revision(s) 39200: [Backport #8080]
* configure.in: move OS specific header/function knowledge before automatic header tests.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39847 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 39200: [Backport #8080]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39847 b2dd03c8-39d4-4d8f-98ff-823fe69b080e