httpdunit: add CMake support for Windows

Add a CMake version of the httpdunit build system. At the moment, the only
annoyance is that CMake doesn't like globbing source files, so the
generator must be re-run whenever test cases are added.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/httpdunit@1796206 13f79535-47bb-0310-9956-ffa450edef68