[llvm] [RISCV] Add TuneJumpIsExpensive (PR #191374)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

I did a quick evaluation and ran Coremark w/ and w/o `jump-is-expensive` and it shows a stable 1.65% performance gain on an 8-wide OoO RISC-V CPU.

https://github.com/llvm/llvm-project/pull/191374