Summary:
There may be cases in which a user wants to know which part of their code is unstable.
We use ObservedFuncs and UnstableCounters to print at exit which of the ObservedFunctions
are unstable under the -print_unstable_stats flag.
Patch by Kyungtak Woo (@kevinwkt).
Reviewers: Dor1s, metzman, morehouse
Reviewed By: Dor1s, metzman, morehouse
Subscribers: delcypher, #sanitizers, llvm-commits, kcc
Differential Revision: https://reviews.llvm.org/D50264
llvm-svn: 339081