[llvm] [RISC-V] Adjust trampoline code for branch control flow protection (PR #141949)

[Kito Cheng via llvm-commits]

kito-cheng wrote:

> Is gcc going to make the same change?

Yes, the code sequence used in GCC  was designed for our internal fixed-one label scheme, that's not work for func-sig based scheme, so the only way is using sw-guarded jump here I think.

https://github.com/llvm/llvm-project/pull/141949