Fix the case where we generate both a 401 and 413 and we go bonkers.

Fix the case where we generate both a 401 and 413 and we go bonkers.

- If an error would drop the connection, we do not return the top-level
  error anymore as we will assume this new one takes precedence over the
  original error.  This also ensures that we will not read the input
  body (which is the point of returning these special error messages in
  the first place).
- The ap_discard_request_body return value in ap_die() must be checked
  to make sure we don't encounter this recursive case and print two errors.

Kudos to Jeff Trawick for his sample input which pointed this out.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95426 13f79535-47bb-0310-9956-ffa450edef68