[clang] [llvm] Reland "[ORC] Track __emutls_t definitions in IRMaterializationUnit" (#207161) (PR #208413)

[Lang Hames via cfe-commits]

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

Otherwise LGTM. The Linux test failure looks unrelated to me.

Thanks very much @conrade-ctc!

https://github.com/llvm/llvm-project/pull/208413