[clang] [llvm] Reland "[ORC] Track __emutls_t definitions in IRMaterializationUnit" (#207161) (PR #209717)

[Emery Conrad via cfe-commits]

conrade-ctc wrote:

@vgvassilev @lhames — this is the reland of #208413 (reverted in #209260 just before the 23.x cut). The Darwin-only symbol fix left the same `__emutls_get_address` gap on compiler-rt-rtlib ELF hosts (the arm-toolchain CI caught it on Linux/AArch64), so this broadens the workaround to all in-process Unix hosts and drops the `isOSBinFormatMachO()` guard — with emulated TLS forced on, a target-format check only re-excludes the hosts that fail. There's an "Alternatives considered" note in the description on loading the builtins archive into a JITDylib instead; glad to go that route if you'd prefer it. Would appreciate a look when you have a moment.


https://github.com/llvm/llvm-project/pull/209717