Reviewed By: Brian Behlendorf, Jim Jagielski

Update mod_negotation.c to support variants with multiple language
types. Languages can either be obtained from file extensions
(eg foo.fr.en.html) or on the Content-Language line in a type-map
file (eg Content-Language: fr, en).

This patch:

* Allows multiple comma separated languages on the Content-Language:
  header in a type-map file

* Updates the function which sets the language quality factor for
  each variant to select the best (highest q) match from the tags
  of the variant, using the algorithm in HTTP/1.1 14.4

* If the new (HTTP/1.1) language negotiation results in a tie between
  variants, falls back onto the Apache 1.1 language negotiation
  algorythm, using _just_ the first language of the variant

* Updates the 406 text and Alternates header to list multiple languages
  if necessary


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@76926 13f79535-47bb-0310-9956-ffa450edef68