[llvm] [LoopIdiomVectorize] Fix FindFirstByte successors (PR #156945)

[Sharjeel Khan via llvm-commits]

Sharjeel-Khan wrote:

I tested this patch with Android builds. It fixed the original issue and there were no new issues arising from the patch. Thanks for fixing this quickly.

https://github.com/llvm/llvm-project/pull/156945