Fix possibly infinite loop in mod_imap. Note that the base

directive in an imagemap file is parsed incorrectly and relative
directories are done incorrectly; this does not fix that, but just
avoids the loop.

Closes PR#130.

Reviewed by: Dean Gaudet, Roy Fielding


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@77619 13f79535-47bb-0310-9956-ffa450edef68