[Support][Test] Time profiler: add regression test

Summary:
Add output to `llvm::errs()` when `-ftime-trace` option is enabled,
add regression test checking this option works as expected.

Reviewers: thakis, aganea

Subscribers: cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D61914

llvm-svn: 362792