[clang] [hwasan] Don't instrument when PGO profile is collected (PR #86739)

[Arthur Eubanks via cfe-commits]

aeubanks wrote:

ah I see. I feel like this should be a more principled approach that other sanitizers also share, as you've mentioned as an alternative. do people not care about other sanitizers in production?

(I'm going to be OOO for a week, so someone else will need to review)

https://github.com/llvm/llvm-project/pull/86739