[clang] [CMake][PGO] Use check targets to generate profdata for PGO builds (PR #77347)

[Chris B via cfe-commits]

llvm-beanz wrote:

Looping in some Apple people. I'm unsure if Apple is still using this infrastructure for generating PGO data. If so this change will impact them. When I wrote this, Apple had some additional test cases that got layered on top of the publicly available tests.

It might make sense to make this configurable by having a user-definable (advanced) variable that specifies which targets to run to generate PGO data.

cc: @ributzka, @Bigcheese

https://github.com/llvm/llvm-project/pull/77347