ncurses 6.2 - patch 20210501

ncurses 6.2 - patch 20210501

+ add a special case in the configure script to work around one of the
  build-time breakages reported for OpenBSD 6 here:
     https://www.mail-archive.com/bugs@openbsd.org/msg13200.html
  There is no workaround for the other issue, a broken linker spec.
+ modify configure check for libtool to prevent accidental use of an
  OpenBSD program which uses the same name.
+ update config.guess, config.sub