[llvm] [NFC] Add a pre-commit test case for #111696 (PR #136730)

[Amy Kwan via llvm-commits]

https://github.com/amy-kwan commented:

I have a suggestion for the patch description.
> Add a pre-commit test case for https://github.com/llvm/llvm-project/pull/111696
> 
>This test case tests that the `ppc-vsx-fma-mutate` pass does not hoist `xxspltiw` instructions out of loops when ran with the `schedule-ppc-vsx-fma-mutation-early` pass.

Is this acceptable? 

https://github.com/llvm/llvm-project/pull/136730