[llvm] [RISCV] Enable tail folding by default (PR #151681)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> Thanks everyone who's worked on this, there's been a lot of contributors over the years [since the first phabricator patch in 2021!](https://reviews.llvm.org/D99750?)
> 
> We still have plenty to do in #123069, and I'm optimistic we can get much of it in for LLVM 22.

Thank you very much, Luke, for enabling it by default. And thanks to all the engineers who made it possible, @Mel-Chen, @arcbbb, @ElvisWang123, @preames, @npanchen, and many others!

https://github.com/llvm/llvm-project/pull/151681