[llvm] [GISel][RISCV] Legalize `G_{U|S}DIVREM` (PR #93067)

[Angelo Bulfone via llvm-commits]

boomshroom wrote:

Is there any good reason why it always generates separate lib calls for div and rem rather than a single line call for divrem?

https://github.com/llvm/llvm-project/pull/93067