win32: clock: apply the clock-source option and remove slow "wall" option

The "clock-source" option is currently not doing anything (using the default) as it's read before we parse all the available options. It's the same thing for the "high-priority" option.

Also remove the "wall" clock-source option which is slower than "perf" and doesn't add any extra precision. The other clock sources with ~10 ms granularity may not be of much use to count time differences in the player.

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v3:

• removed tick and interrupt clock sources as their resolution is too small to be useful
• brought back multimedia clock source as it might be needed when perf is not reliable (it was the default in 3.0)
• multimedia now links statically with winmm.dll while in older versions it was loading it dynamically

v4:

• removed the patch that removed the var_InheritXXX calls as it doesn't use the default value
• added more doc in the patch bringing back the "multimedia" clock source