systemclock: Use high resolution timer on Windows if possible

Default Windows' system timer has poor resolution (less than about 16ms)
which is not suitable for media processing.
To use high-resolution timer on Windows, we need to make use of timeBeginPeriod() API

NOTE: timeBeginPeriod() will change global system setting, that means
other applications on the system will be affected. If user doesn't
want to change global system setting, "GST_DISABLE_WINMM_CLOCK_TIMER"
environment can be used for the purpose.

NOTE: After the use of updated system clock precision, we will
restore the previous setting by using timeEndPeriod()