This fixes a failed assert when r->remaining is left in a negative

state and we hit some other error (like permission failure) causing
an internal redirect causing us to reevaluate the input buffers
(for discarding the request body).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95419 13f79535-47bb-0310-9956-ffa450edef68