Update to isl 1b3ba3b72c0482fd36bf0b4a1186a259f7bafeed

This includes the following very useful isl commit:

commit d962967ab42323ea5ca0398956fbff6a98c782fa
Author: Sven Verdoolaege <skimo@kotnet.org>
Date:   Wed Dec 18 12:05:32 2013 +0100

allow the user to impose a bound on the number of low-level operations

This should allow the user to deterministically limit the effort spent on a
computation.

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@200155 91177308-0d34-0410-b5e6-96231b3b80d8
Dependences: Bound the time dependence calculation is allowed to take

Count the number of computational steps that have been used to solve the
dependence problem and abort in case we reach the "compute-out". This ensures we
do not hang forever in cases the dependence problem is too difficult to solve.
There is just a single case in the LLVM test-suite that runs into the
compute-out. Even in this case, we can probably coalesce some of the parameters
(i32 b, i32 b zext i64, ...) to simplify the problem enough to not hit the
compute out. However, for now we set the compute out in place to address the
general issue. The compute out was choosen such that it stops on a recent laptop
after about 8 seconds.

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@200156 91177308-0d34-0410-b5e6-96231b3b80d8