Allow non-affine control flow -- SCoP Detection

  With this patch we allow the SCoP detection to detect regions as SCoPs
  which have non-affine control flow inside. All non-affine regions are
  tracked and later accessible to the ScopInfo.

  As there is no real difference, non-affine branches as well as
  floating point branches are covered (and both called non-affine
  control flow).  However, the detection is restricted to
  overapproximate only loop free regions.

llvm-svn: 230325