Metal: Remove obsolete compile guards from the command buffer memoryBarrierWithScope and memoryBarrierWithResources: - macOS 10.14 (min compile 12.0, min deploy 10.15) - iOS/tvOS 12.0 (min compile 17.0, min deploy 15.0) dispatchThreads: - macOS 10.13 (min compile 12.0, min deploy 10.15) - iOS 11.0 (min compile 17.0, min deploy 15.0) - tvOS 14.5 (min compile 17.0, min deploy 15.0) Bug: angleproject:360147119 Change-Id: I05e4e5dac81b4e07c47e0f3a1b7d165ff9406cc3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5804021 Reviewed-by: Kimmo Kinnunen <kkinnunen@apple.com> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Alexey Knyazev <lexa.knyazev@gmail.com>