[clang] [Sema] Mark alias/ifunc targets used and consider mangled names (PR #87130)

[Mehdi Amini via cfe-commits]

joker-eph wrote:

This broke a bot, I reverted and it's back green here: https://lab.llvm.org/buildbot/#/builders/272/builds/14069

https://github.com/llvm/llvm-project/pull/87130