[clang] [llvm] Remove mmx 3dnow (PR #96246)

[Phoebe Wang via llvm-commits]

https://github.com/phoebewang commented:

This is much like what we have removed for KNL intrinsics/instructions., so general LGTM. But I'd like Simon to sign off given I'm not familar with 3DNOW instructions.

https://github.com/llvm/llvm-project/pull/96246