+ add a null-pointer check for term_names field in copy_termtype(),
needed for MinGW port (report by Peiyuan Song, cf: 20220521).
+ revise kon/kon2/jfbterm to undo "linux2.6" change to
smacs/rmacs/enacs (Debian #1012800) -TD
+ amended note for att610+cvis0, as per documentation for att610,
att620, att730 -TD