Change license from GPL 2.0 to GPL 2.0+
In particular, relicense the code that was copied from PolyLib
when it was GPL 2.0 only or that was contributed directly to barvinok
around that time.
Additionally, move count_points_e (based on PolyLib's count_points)
to evalue.c so that all contributed code is in a single file.
Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>
Signed-off-by: Doran Wilde <doran_wilde@byu.edu>
Signed-off-by: Vincent Loechner <loechner@gauvain.u-strasbg.fr>
Signed-off-by: Emmanuel Jeannot <emmanuel.jeannot@labri.fr>
Signed-off-by: Rachid Seghir <rachid.seghir@gmail.com>