mod_negotiation marks *all* responses

(HTTP/1.0) browsers and proxies caching one variant which may not be the
correct one for subsequent requests. The issue is that if you are using
mod_negotiation in a trivial way to map (say) requests for index onto
index.html *with no other variants*, Apache makes your responses
non-cacheable when they probably are safely cacheable.

This patch makes responses from mod_negotiation cacheable in the following
circumstances:

  *  Variants are found by multiviews (i.e. looking on the disk, rather
     than reading a .var file) AND
  *  there was only one matching variant found on disk AND
  *  request version is HTTP/1.0 or earlier

Reviewed By: Roy Fielding, Dean Gaudet


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79030 13f79535-47bb-0310-9956-ffa450edef68