Fixed failure on Darwin due to r354064

Summary:
instrprof-darwin-exports.c test fails on Darwin due  to r354064.

Updated clang list of exported symbols to fix the issue.

Reviewers: vsk

Reviewed By: vsk

Subscribers: davidxl, efriedma

Differential Revision: https://reviews.llvm.org/D58259

llvm-svn: 354089