Use wrapped reduction dependences

  This change will ease the transision to multiple reductions per statement as
  we can now distinguish the effects of multiple reductions in the same
  statement.

  + Wrapped reduction dependences are used to compute privatization dependences
  + Modified test cases to account for the change



git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@211795 91177308-0d34-0410-b5e6-96231b3b80d8