merge revision(s) 39174: [Backport #8080]

	* configure.in: move header files check to the beginning of
	  "header and library section".
	  test rlim_t with sys/types.h and sys/time.h for MirOS BSD.
	  sys/types.h and sys/time.h is gurded by #ifdef and the above move
	  is required for this change.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39846 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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