[clang] [CIR][NEON] Add lowering for `vnegd_s64` and `vnegh_f16` (PR #180597)

[Andrzej Warzyński via cfe-commits]

banach-space wrote:

The CI failure is unrelated to this PR, so landing. I've posted a reverting PR for the breaking change here: https://github.com/llvm/llvm-project/pull/180916

https://github.com/llvm/llvm-project/pull/180597