sys/directsound/gstdirectsoundsink.*: Add an attenuation property that will directly attenuate the directsound buffer.

Original commit message from CVS:
* sys/directsound/gstdirectsoundsink.h:
* sys/directsound/gstdirectsoundsink.c:
Add an attenuation property that will directly attenuate the
directsound buffer.
Change the size of the directsound secondary buffer to a half second.
Add more debug logs.
Add a lock to protect dsound buffer write access.
Fix a bad implementation of reset.
* sys/directsound/gstdirectdrawsink.c:
* sys/directsound/gstdirectdrawsink.h:
Add a keep_aspect_ratio property.
Do not use overlay if not supported.
Add more debug logs.
Remove overwrite of WM_ERASEBKGND message handling. It was not
redrawing border when keep_aspect_ratio was enabled.
* win32/common/config.h:
update version waiting an auto-generated config.h