[RISCV] Support select optimization
AArch64 has enabled this in https://reviews.llvm.org/D138990, and
the measurement data still stands for RISCV in some cases.
And, similar optimization like #77284 is added too.
After this patch, the highly predictable branch will be converted
back to branches instead using selects.
This pass is disabled by default now, we can enable it by default
after more detailed investigation.
Reviewers: davemgreen, preames, dtcxzyw, lukel97, topperc, asb
Pull Request: https://github.com/llvm/llvm-project/pull/80124
