Change mod_rewrite to use apr-util's dbm support for dbm rewrite

Change mod_rewrite to use apr-util's dbm support for dbm rewrite
maps.

For now, the SDBM dbm flavor is always used.  It won't be compatible
with dbm rewrite maps built for Apache 1.3 until apr-util supports
ndbm and mod_rewrite is changed to prefer ndbm over the built-in
sdbm.

PR:         10644

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96478 13f79535-47bb-0310-9956-ffa450edef68