[llvm] [RISCV] Add TuneNoDefaultUnroll to generic CPUs (PR #135318)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

> https://lnt.lukelau.me/db_default/v4/nts/665?compare_to=656
> 
> Some big regression in code size with rva22u64_v -O3 -flto. Only regression in exec time was 523.xalancbmk_r but we know that benchmark is usually noisy

The code size regressions are expected, the performance has no observable change possibly because Spacemit X60 is just a dual-issues in-order core.
I don't know if there are some data from other CPUs?

https://github.com/llvm/llvm-project/pull/135318