The spec was clarified that a value of .5 rounds towards the even value.
This matches the HLSL `round` method. This CL updates SPIR-V to use the
`RoundEven` GLSL450 call and the `rint` MSL call so they match the spec
requirements.
Change-Id: I97ce2e29b9639ad72b6846b32dbe3abb8d9f6cff
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42421
Auto-Submit: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Ryan Harrison <rharrison@chromium.org>