Add cmake build for APR-Util 1.5.x.

*.hwc files are essentially the same as the existing .hw
files, except for a few variables filled in during cmake
configuration.

tdonovan contributed a lot via a previous experiment with
cmake.


git-svn-id: https://svn.apache.org/repos/asf/apr/apr-util/branches/1.5.x@1518770 13f79535-47bb-0310-9956-ffa450edef68