[llvm] [LoongArch] Support emulated TLS (PR #92483)

[Lu Weining via llvm-commits]

SixWeining wrote:

> Can we (and preferably also the OHOS porters) sort out and try to remove the emulated TLS usage in the OHOS codebase instead? At least we would know exactly why it is necessary if it eventually turns out to be the case.

I heard that currently some services in OHOS use **coroutine** which depends on emulated TLS, but I don't know the details. I also heard they plan to remove the dependency and switch to ELF TLS in future versions.

So I prefer reporting error in somewhere (ether in clang or backend) if emulated TLS is used on LoongArch.

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