isl_test.c: test_lexmin: abort on failed test
isl_test.c: test_lexmin: abort on failed test

The test case would result in an assertion failure prior
to the commit in which it was introduced, isl-0.02-73-ge18f50ef6
(isl_sample.c: initial_basis: set n_unbounded and n_zero,
Sat Apr 10 15:44:03 2010 +0200).
However, the test should also cause isl_test to fail
if anything else goes wrong.

Signed-off-by: Sven Verdoolaege <235c10dd23b819f81cdc9756a251746bc184cab6@gmail.com>

Meinersbur/isl,Meinersbur/isl,Meinersbur/isl,Meinersbur/isl