Pass AssumptionCacheTracker from SampleProfileLoader to Inliner

Summary: Inliner needs ACT when calling InlineFunction. Instead of nullptr, we need to pass it in from SampleProfileLoader

Reviewers: davidxl

Subscribers: eraman, vsk, danielcdh, llvm-commits

Differential Revision: http://reviews.llvm.org/D21205

llvm-svn: 273199