[lld] [RISCV][LLD] Add RISCV zcmt optimise in linker relaxation (PR #77884)

[via llvm-commits]

Xinlong-Wu wrote:

I'm trying remove the symble `.riscv.jvt` when Jump table is empty, But I have noticed `.shStrTab` has been fixed befor relaxation. I can't remove it from string table. string `.riscv.jvt` in `.shStrTab` will always cause a negative effect

https://github.com/llvm/llvm-project/pull/77884