[llvm] [instcombine][x86]: simplifyx86fpmaxmin - allow negzero for single operand (PR #180418)

[Simon Pilgrim via llvm-commits]

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

please can you add scalar intrinsic test coverage - only the 0th element needs to match the fpclass in those cases

https://github.com/llvm/llvm-project/pull/180418