isl_basic_map_realign: perform Gaussian elimination on result
Many parts of isl assume that Gaussian elimination has been
applied to the equality constraints. In particular singleton_extract_point
makes this assumption. The input to singleton_extract_point
may have undergone parameter alignment. This parameter alignment
(ultimately performed by isl_basic_map_realign) therefore
needs to make sure the result preserves this property.
Reported-by: Tobias Grosser <tobias@grosser.es>
Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>