Fix negotiation so that we prefer an encoded variant over an unencoded

variant if the user-agent explicitly says it can accept that encoding.
Previously we always preferred the unencoded variant.

PR:		3447
Submitted by:	Paul Ausbeck <paula@alumni.cse.ucsc.edu>
Reviewed by:	Paul Sutton


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@82443 13f79535-47bb-0310-9956-ffa450edef68