[llvm-branch-commits] [X86][NewPM] Port X86FlagsCopyLowering to NPM (PR #173752)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/173752

As the title says. Take a couple of existing tests that run solely this
pass and use them for test coverage.