makefile.win: Adjust makefile to properly detect the need to use devenv
on applicable MSVC versions.

trunk patch: http://svn.apache.org/r1482041
Submitted by: gsmith
Reviewed by: jim, minfrin


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1486938 13f79535-47bb-0310-9956-ffa450edef68