[RTC] Use the domain to split alias groups.

  We use a parametric abstraction of the domain to split alias groups
  if accesses cannot be executed under the same parameter evaluation.

  The two test cases check that we can remove alias groups if the
  pointers which might alias are never accessed under the same parameter
  evaluation and that the minimal/maximal accesses are not global but
  with regards to the parameter evaluation.

Differential Revision: http://reviews.llvm.org/D5436