[llvm-branch-commits] [clang] [Clang][RISCV] Refactor builtins to TableGen (PR #80280)

[Wang Pengcheng via llvm-branch-commits]

https://github.com/wangpc-pp created https://github.com/llvm/llvm-project/pull/80280

This mechanism is introduced by #68324.

This refactor makes the prototype and attributes clear.