[PM] Make the new-pm passes behave more like the legacy passes

Summary:
Testing the new-pm passes becomes much easier once they behave more like the
old passes in terms of the order in which Scops are processed and printed. This
requires three changes:
- ScopInfo: Use an ordered map to store scops
- ScopInfo: Iterate and print Scops in reverse order to match legacy PM behaviour
- ScopDetection: print function name in ScopAnalysisPrinter

Reviewers: grosser, Meinersbur, bollu

Reviewed By: grosser

Subscribers: pollydev, llvm-commits

Differential Revision: https://reviews.llvm.org/D36303

llvm-svn: 310052