mod_dbd: Backport of r708820 from trunk to avoid compiler warnings

with strict compilers like Sun Studio. Reported on the list by Jie Gao.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@819429 13f79535-47bb-0310-9956-ffa450edef68