mod_slotmem_shm: Remove the colon syntax to indicate a relative path, and

make the relative path default behaviour. Remove the word "anonymous" as
a filename for special treatment, what used to be "anonymous" is now "none".


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1210261 13f79535-47bb-0310-9956-ffa450edef68