[clang] [llvm] [RISCV] Xqccmp Code Generation (PR #128815)

[Sam Elliott via cfe-commits]

lenary wrote:

@topperc the two useful changes since you last reviewed are:
- Adding a Release Note
- Changing the conditions around frame pointers to ensure we don't emit a `add s0, sp, -<size>` (as before), but that we do emit the `.cfi_def_cfa s0, 0` which informs dwarf/cfi that the way to calculate the CFA is with `s0` (the usual way when `hasFP(MF) == true`).

https://github.com/llvm/llvm-project/pull/128815