[graphite] discard scops for which entry==exit

[graphite] discard scops for which entry==exit

In this patch we discard the scops where entry and exit are the same BB.
This is an effort to remove graphite-scop-detection.c:limit_scops.
Removing the limit_scops function introduces correctness regressions.
We are making relevant changes in incremental steps to fix those bugs,
and finally we intend to remove limit_scops.

2015-06-29  Aditya Kumar  <aditya.k7@samsung.com>
                Sebastian Pop <s.pop@samsung.com>

        * graphite-scop-detection.c (build_scops_1): Discard scops for which entry==exit

Co-Authored-By: Sebastian Pop <s.pop@samsung.com>
From-SVN: r225850