GBE: structurized loop exit need an extra branching instruction when do reordering.

GBE: structurized loop exit need an extra branching instruction when do reordering.

When we want to reorder the BBs and move the unstructured BB out-of the
structured block, we need to add a BRA to the block. If the exit of the
structured block is a loop, we need to append a unconditional BRA right
after the predicated BRA. Otherwise, we may lost the correct successor
if an unstructured BB is moved next to this BB.

After this patch, with loop optimization enabled, there is no regression
on both utests and piglit. But there are still a few regressions in opencv
test suite:
[----------] Global test environment tear-down
[==========] 8 tests from 2 test cases ran. (40041 ms total)
[  PASSED  ] 2 tests.
[  FAILED  ] 6 tests, listed below:
[  FAILED  ] OCL_Photo/FastNlMeansDenoising.Mat/2, where GetParam() = (Channels(2), false)
[  FAILED  ] OCL_Photo/FastNlMeansDenoising.Mat/3, where GetParam() = (Channels(2), true)
[  FAILED  ] OCL_Photo/FastNlMeansDenoisingColored.Mat/0, where GetParam() = (Channels(3), false)
[  FAILED  ] OCL_Photo/FastNlMeansDenoisingColored.Mat/1, where GetParam() = (Channels(3), true)
[  FAILED  ] OCL_Photo/FastNlMeansDenoisingColored.Mat/2, where GetParam() = (Channels(4), false)
[  FAILED  ] OCL_Photo/FastNlMeansDenoisingColored.Mat/3, where GetParam() = (Channels(4), true)

So let's keep this optimizaion disabled. Will enable it when I fixed all
the known issues.

Signed-off-by: Zhigang Gong <zhigang.gong@intel.com>
Reviewed-by: Luo <xionghu.luo@intel.com>