Update to version 0.99.21
    
    - Add babeld (Babel routing protocol daemon, RFC 6126)
    - Use .tar.xz source distribution
    - Drop all patches (included upstream)
    - Move watchquagga to -sysvinit
      (The systemd service files are now configured to automatically
      restart any daemon on failure. If zebra fails, all running
      daemons will be stopped; zebra will be started again; and then
      the previously running daemons will be started again.)