[llvm] PPC750cl, and initial support for paired singles (PR #211463)

[Cynthia Coan via llvm-commits]

Mythra wrote:

Sorry about the formatting failure, I could've sworn I had run clang-format before hand. Anyway, the command previously reporting an error doesn't, I also rebased against latest main since there were no comments or reviews that could potentially get messed up, and it'll make it easier if this PR lasts as long as it has again.

https://github.com/llvm/llvm-project/pull/211463