[clang] [llvm] [WIP][RISC-V] prototyping support for Zvbc32e and Zvkgs (PR #128243)

[Nicolas Brunie via cfe-commits]

nibrunieAtSi5 wrote:

This PR is built has a porting to main of a branch which was originally created on top of llvm 18.1.8 tag (the top tag in riscv-gnu-toolchain when this effort was started). It looks like a few changes (including opcodes for the Zvkgs) did not make it properly to the port.

https://github.com/nibrunie/llvm-project/commits/riscv-zvbc32e-zvkgs-proto_from_llvmorg-18.1.8/

https://github.com/llvm/llvm-project/pull/128243