Make the CMake build (tentatively) work on Windows.

* build/FindAPR.cmake, build/FindAPRUtil.cmake: Support Windows.
* build/SerfPlatform.cmake: Add module for platform detection.
* build/APRCommon.cmake (_apru_version): New utility function.
* CMakeLists.txt: Update for Windows.

git-svn-id: https://svn.apache.org/repos/asf/serf/trunk@1834439 13f79535-47bb-0310-9956-ffa450edef68
5 files changed