Fix these three problems with the makefiles:

   - regex is always rebuilt
   - os/unix doesn't clean up for itself, instead relies on the top level to
     clean up.
   - the top level should clean itself only and recurse, not delete lower
     level objects.

Submitted by:	Dean Gaudet


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79200 13f79535-47bb-0310-9956-ffa450edef68