Add cmake build for APR 1.4.x.

apr.hwc is the same as apr.hw other than making the APR_HAVE_IPV6
setting a variable.

This is not currently in the 1.5.x branch, which sees little
use.


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.4.x@1518760 13f79535-47bb-0310-9956-ffa450edef68