[llvm] [X86] Add custom operation actions for f16: FABS, FNEG, and FCOPYSIGN (PR #128877)

[Simon Pilgrim via llvm-commits]

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

You need to run`ninja check-llvm-codegen-x86` and update any of the test files that have changed, you should be able to use the `llvm-project\llvm\utils\update_llc_test_checks.py` script

https://github.com/llvm/llvm-project/pull/128877