fix cache confusion which happens if different virtualhosts define

rewritemaps with the same name.
This is done using name mangling. For the cache we prefix the map name
with the hex value of the current server struct pointer. This way
inherited maps still use the same cache.

PR: 26462


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@103335 13f79535-47bb-0310-9956-ffa450edef68