Update asciidoc processing from locale module.
    
    - Previously, a plain/text mime verification was applied against
      incoming files. This worked well for articles and manpages documents
      written in asciidoc format but it failed for manpage documents
      written in asciidoc format which first line is prepare(1). In this
      last case, even the incoming file is visibly a plain/text file, the
      command file interprets it as an image/x-3ds file which made
      plain/text mime verification to fail. This update changes the
      verification from mime to match, using the incoming file extension
      as reference, in order for manpage documents with prepare(1) as
      first line to succeed localization update.