Make new PM honor -fdebug-info-for-profiling

Summary: The new PM needs to invoke add-discriminator pass when building with -fdebug-info-for-profiling.

Reviewers: chandlerc, davidxl

Reviewed By: chandlerc

Subscribers: sanjoy, llvm-commits

Differential Revision: https://reviews.llvm.org/D35744

llvm-svn: 309121