[FIX] Adjust the insert point for non-affine region PHIs

  If a non-affine region PHI is generated we should not move the insert
  point prior to the synthezised value in the same block as we might
  split that block at the insert point later on. Only if the incoming
  value should be placed in a different block we should change the
  insertion point.

llvm-svn: 265132