Update git submodules

• Update extensions/ImageMap from branch 'REL1_29'
  • Use LIBXML_NOEMPTYTAG to avoid creating self-closing <a> tag
    
    Browsers just treat the self-closed <a> tag as only the open tag, so anything after the map would become linked.
    
    tidy normally cleans this up, but other wikis without it, or those using RemexHtml would see this issue.
    
    Fix suggested by Phabricator user Porplemontage
    
    Bug: T136855 Change-Id: I3b00e1a9cbb096afebe37614a79548f64d561e3b (cherry picked from commit 2ba1d20fcde046c0f8dc813d0d723c5858805ccd)