Test for error conditions before creating output header fields, since

we don't want the error message to include those fields.  Likewise,
reset the content_language(s) and content_encoding of the response
before generating or redirecting to an error message, since the new
message will have its own Content-* definitions.

This is only a partial solution to the problem of error messages
inheriting header fields and request_rec variables from almost-succeeded
requests, but this part is needed for the general solution anyway.
A fix for the latter will be in a separate patch.

Submitted by: Dean Gaudet
Reviewed by: Roy Fielding, Ken Coar, Jim Jagielski


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@78125 13f79535-47bb-0310-9956-ffa450edef68