[compiler-rt] [RISCV] Support rv{32, 64}e in the compiler builtins (PR #88252)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

> @wangpc-pp thanks for merging! Should this be backported to `release/18.x`?

Yeah, I think so! We have supported RVE in 18.x, but it isn't fully supported without this change.

https://github.com/llvm/llvm-project/pull/88252