- change the prototype for apr_dbm_geterror() [and update dav/fs/dbm.c]

- fix up some error handling in apr_dbm.c
- use "dbm" consistently for the apr_dbm_t parameter


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87814 13f79535-47bb-0310-9956-ffa450edef68