Fix build breakage on Linux glibc 2.1+ systems that prevented db1 from being

correctly found for mod_auth_dbm.  This is similar to the mod_auth_db check.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@90442 13f79535-47bb-0310-9956-ffa450edef68