Fix out-of-range access in test case

The function use_after_scop would iterate from 0 to 1024 and accessing element A[1024] where A has only valid indexes from 0 to 1023. Polly detects the situation of unconditionally undefined behavior and bail out in ScopInfo as non-feasible for optimization.

Other tests add impossible context assumptions as well, hance might show the same problem.

llvm-svn: 247412