p = vlc.Position(value=16, origin=vlc.RelativePosition)
Defaults to value=0, origin=AbsolutePosition, key=MediaTime

* win32_specific.c, threads.c: fix win32 compilation.

* Some more fixes (+ don't redefine a function that already existed, reverts part of previous commit).

It is by design flawed to have phony built source.

		   Revert [20203]

I find the original semantic a bit suspicious, but someone should really double check this commit and revert if needed.