+20210710
+ + improve history section for tset manpage based on the 1BSD tarball,
+ which preceded BSD's SCCS checkins by more than three years.
+ + improve CF_XOPEN_CURSES macro used in test/configure (report by Urs
+ Jansen).
+ + further improvement of libtool configuration, adding a dependency of
+ the install.tic rule, etc., on the library in the build-tree.
+ + update config.sub
+