Update brltty to version 6.4 / rev 58 via SR 953980
    
    https://build.opensuse.org/request/show/953980
    by user mgorse + dimstar_suse
    - Pass --with-tables-directory=%{_datadir}/%{name} to configure: do
      not install the tables to /etc, as they are not supposed to be
      modified by local admins. (forwarded request 953158 from dimstar)