Beware: the dEQP tests here are very weak - they do not seem to properly test the NaN handling of this instruction.

Bug: b/126873455
Tests: dEQP-VK.spirv_assembly.instruction.compute.opnmax.all
Change-Id: Ibd704c9dc9c3475df10b02c0c0f80b9c3e472ff4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28710Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>