Reanimate the DBM support for RewriteMap in mod_rewrite by fixing two source

code errors and making sure it is disabled when DBM support is not available
on the used platform.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@80397 13f79535-47bb-0310-9956-ffa450edef68