[llvm] [LoongArch] Emit error messages when using emulated TLS (PR #92483)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> > Instead of an error for each TLS instance, emit it in TargetMachine ?
> 
> I didn't find a way to emit an error message and return the error to the error handler. Either use `report_fatal_error` ?

Seems fine. report_fatal_error with false `GenCrashDiag`?

https://github.com/llvm/llvm-project/pull/92483