Code a bit more defensively. If dav_lookup_uri() ever placed user

input into lookup.err.desc for the HTTP_BAD_REQUEST case, then we
could have problems (via a format string attack). This change frees us
from *future* worries.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97233 13f79535-47bb-0310-9956-ffa450edef68