- On Apple GPUs, set timestampPeriod to 1.0.
- On non-Apple GPUs, calculate timestampPeriod each time it is retrieved.
- On older devices that do not support GPU timestamps, use nanosecond
CPU timestamps to be consistent with timestampPeriod of 1.0.
- Change MVKConfiguration::timestampPeriodLowPassAlpha and environment
variable MVK_CONFIG_TIMESTAMP_PERIOD_LOWPASS_ALPHA to 1.0, to use
only latest value by default.
- Add build-time verification that MVKConfigMembers.def
includes all members of MVKConfiguration (unrelated).