[llvm] [X86][ABIVerifier] Verify floating point ABI correctness on 64-bit target (PR #111690)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

This has no place in the IR verifier. There could be a dedicated ABI linting pass, but this should not be considered invalid IR.

This also needs to use the backend parsing for target-features, which accounts for target-cpu as well as target-features. Clang spams redundant target-features entries with target-cpu, but this is not required 

https://github.com/llvm/llvm-project/pull/111690