Analyze only those bbs which are outside the region for uses which might be
defined inside the region. This is intended to improve the compile time. This
algorithm may be further improved by only looking at the successors of region as
these regions are sese. Added FIXMEs to make this improvement in future.

Passes regtest and bootstrap on x86_64.

gcc/ChangeLog:

2015-10-05  Aditya Kumar  <hiraditya@msn.com>

        * graphite-sese-to-poly.c (build_loop_iteration_domains): Only loops
        which are in this region are passed so gcc_assert and remove redundant
        computation.
        * sese.c (sese_build_liveouts): Pass only those bbs which are not in region.
        (sese_bad_liveouts_use): Only BBs which are not in region are passed so
        gcc_assert on that and remove unnecessary computation.
        (sese_build_liveouts_use): Same.

From-SVN: r228529