timeBeginPeriod() only allows setting minimum timer resolution
to 1 ms. However, modern x86 platforms support a minimum timer
resolution of 0.5 ms. Use NtSetTimerResolution() instead for
the increased resolution, which can be set with MPV_HRT_RES.
Additionally, change the units of mp_start_hires_timers(),
mp_end_hires_timer(), MPV_HRT_RES, and MPV_HRT_MAX to nanoseconds,
in accordance with other functions used in timer.h.