[NFC][ScopBuilder] Move addUserAssumptions to ScopBuilder

Scope of changes:
1) Moved addUserAssumptions function to ScopBuilder class.
2) Moved buildConditionSets functions to polly namespace.
3) Moved getRepresentingInvariantLoadSCEV to public section of the Scop class

Differential Revision: https://reviews.llvm.org/D65241

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@368089 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed