[clang] [llvm] Revert 159f1c048e08a8780d92858cfc80e723c90235e3 (PR #173893)

[Walter Lee via cfe-commits]

googlewalt wrote:

Thanks.  The FDO reproducer is difficult to reduce, but I'll see if I can find and reduce an internal failure that doesn't involve FDO.

https://github.com/llvm/llvm-project/pull/173893