Add an "installdll" target to build the DLL used by the installshield

2 configuration. This is not built as part of the normal "_apacheX" or
"installX" builds.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@80315 13f79535-47bb-0310-9956-ffa450edef68