gtx: link against libtinfo if termlib is seperated

gtx: link against libtinfo if termlib is seperated

If ncurses is built with "./configure --with-termlib=tinfo", gtx fails
to link because of an undefined reference to the LINES symbol which is
then provided by libtinfo.so and not libncurses.so.

If ncurses is present, additionally check whether LINES is provided by
ncurses or tinfo and set $LIB_curses accordingly.

This change is based on a patch provided by Bastian Beischer.

FIXES 134420

Reviewed-on: https://gerrit.openafs.org/12760
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 311f1d28a2f626350b33ad432e674055b62511bd)

Change-Id: I2f69fe51bbefeeb2a17145a88aa9c891644f2f61
Reviewed-on: https://gerrit.openafs.org/12763
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Laß <lass@mail.uni-paderborn.de>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>