Remove the MaxLoopDepth attribute from the TempScop class

  Now MaxLoopDepth only lives in Scops not in TempScops anymore.
  This is the first part of a series of changes to make TempScops
  obsolete.

Differential Revision: http://reviews.llvm.org/D6069


git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@221026 91177308-0d34-0410-b5e6-96231b3b80d8