[llvm] [llvm-c] Add EmulatedTLS and EnableTLSDESC to LLVMTargetMachineOptions (PR #161155)

[Julien Portalier via llvm-commits]

ysbaddaden wrote:

After further code reading and testing, the default configuration for the triple, such as `hasDefaultEmulatedTLS`, was never considered when creating the target options. I must enable EmulatedTLS for the `__emutls_*` symbols to show up when compiling for the `x86_64-opensd` target for example.

The updated patch now uses `std::optional` to know if the values have been explicitly set then ask the target triple, in the same vein as `llvm::codegen::InitTargetOptionsFromCodeGenFlags()`:

https://github.com/llvm/llvm-project/blob/20aff2085c358d3e112b245494161ddb9ffe0410/llvm/lib/CodeGen/CommandFlags.cpp#L617-L620

https://github.com/llvm/llvm-project/pull/161155