Hybrid dependency analysis

  This dependency analysis will keep track of memory accesses if they might be
  part of a reduction. If not, the dependences are tracked on a statement level.
  The main reason to do this is to reduce the compile time while beeing able to
  distinguish the effects of reduction and non-reduction accesses.

  + Adjusted two test cases


git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@211794 91177308-0d34-0410-b5e6-96231b3b80d8