[ProfileData] Sort FuncData before iteration to remove non-determinism

Reviewers: rsmith, bogner, dblaikie

Reviewed By: dblaikie

Subscribers: Hahnfeld, jdoerfert, vsk, dblaikie, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D57986

llvm-svn: 355252