Update isl to remove platform dependent behavior

isl commit 9e01482 changed an internal comparision function to ensure
consistent results across different platforms. Differences that have
previously observed between Linux and Solaris 10 should disappear with
the updated isl version.
Update isl

isl commit f5ed5dd6 changed the output of one the test cases. We update
isl and the test case to allow CLooG to be compiled with this and later
versions of isl.
Another isl update that changes cloog's output
Update to isl 0.12

Signed-off-by: Tobias Grosser <tobias@grosser.es>
Fix error with automake 1.13+
Add isl and cloog-isl CMake modules (for CMake find_package function)

NB: the isl module is there for convenience purpose. If it appears
someday in isl itself, it should be removed.