[clang] Avoid Assertion Failure Using -fcs-profile-generate with distributed thin-lto (PR #129736)

[Teresa Johnson via cfe-commits]

https://github.com/teresajohnson approved this pull request.

lgtm with the change suggested by @ellishg to use getProfileGenName. I believe we always specify a profile filename using the `=` form of the option, which is why we have not encountered this issue.

https://github.com/llvm/llvm-project/pull/129736