Allow loops in non-affine subregions -- SCoP Detection

  This will allow the ScopDetection to detect non-affine regions that
  contain loops. All loops contained will be collected and are
  accessible to later passes in order to adjust the access functions.
  As the loops are non-affine and will not be part of the polyhedral
  representation later, all accesses that are variant in these loops
  have to be over approximated as non-affine accesses. They are
  therefore handled the same way as other non-affine accesses.
  Additionally, we do not count non-affine loops for the profitability
  heuristic, thus a region with only a non-affine loop will only be
  detected if the general detection of loop free regions is enabled.

Differential Revision: http://reviews.llvm.org/D8152

llvm-svn: 234711