[ScopBuilder/ScopInfo] Move ScopStmt::buildAccessRelations to ScopBuilder. NFC.
This method is only called in the SCoP building phase.
Therefore it fits better into ScopBuilder to separate
SCoP-construction from SCoP modeling.
This mostly mechanical change makes ScopBuilder directly access some of
ScopStmt/MemoryAccess private fields. We add ScopBuilder as a friend
class and will add proper accessor functions sometime later.
git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@312115 91177308-0d34-0410-b5e6-96231b3b80d8