Fix handling of languages when lang_index == -1 in is_variant_better().

Closes PR#155,94

Submitted by: lampa@fee.vutbr.cz
Reviewed by: Paul Sutton, Marc Slemko, Dean Gaudet


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@77573 13f79535-47bb-0310-9956-ffa450edef68