[llvm] [RISCV][VLOPT] Enable the RISCVVLOptimizer by default (PR #119461)

[Michael Maitland via llvm-commits]

michaelmaitland wrote:

> Have you had a chance to kick the tires with this on llvm-test-suite or SPEC?

I had a chance to run this on spec2006/int/train and spec2017/int/train on qemu. Both build and terminate without errors.

https://github.com/llvm/llvm-project/pull/119461