Added support for modulo expressions

  The support is limited to signed modulo access and condition
  expressions with a constant right hand side, e.g., A[i % 2] or
  A[i % 9]. Test cases are modified according to this new feature and
  new test cases are added.

Differential Revision: http://reviews.llvm.org/D4843


git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@215684 91177308-0d34-0410-b5e6-96231b3b80d8