Subtle variation for security. If the mod_mime file has nothing specific

  Subtle variation for security.  If the mod_mime file has nothing specific
  to say about a given set of file extentions (and has only based the
  resolved fields on the default language, encoding and content type)
  then tell us we can ignore the result by leaving the exception list
  entirely undefined.  If mod_mime adds anything (a language, charset, or
  whatnot) then proceed to use the file in the Multiviews evaluation,
  otherwise mod_negotation will ignore the file found.

  This points out a need for a slightly twisted DefaultClientLanguage,
  as opposed to creating foo.html.html files.  Either that, or introduce
  a 'neutral' entity that the user can list (say, .default) for mod_mime
  to declare it as a fallback language/encoding/content-type/handler.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89919 13f79535-47bb-0310-9956-ffa450edef68