clGetHostTimer returns the current value of the host clock as seen by device.
This value is in the same timebase as the host_timestamp returned from clGetDeviceAndHostTimer.
The implementation will return with as low a latency as possible to allow a correlation
with a subsequent application sampled time. The host timestamp and device timestamp returned
by this function and clGetDeviceAndHostTimer each have an implementation defined timebase.
The timestamps will always be in their respective timebases regardless of which query function
is used. The timestamp returned from clGetEventProfilingInfo for an event on a device and a
device timestamp queried from the same device will always be in the same timebase.