This uncomments the configure checks for HAVE_VDPAU. That way VDPAU can
be used even if libavcodec is missing or old.

This way, common.am can be included also in directories without a
Modules.am file.

These functions assume that sockets are file descriptors, never worked
properly on Windows. See also 3841c085.

This reverts commit db8ff4e3.

refs b2cce4d8

Signed-off-by: Rafaël Carré <funman@videolan.org>

avcodec_flush_buffers() may get or release frame buffers.
See also EndVideoDec().

With the previous commit, the vout wrapper's display pool is no longer
used ever if direct rendering is not in use. Removing it saves one
picture buffer.
Signed-off-by: Rafaël Carré <funman@videolan.org>

When the decoder output and the display video formats are different,
the picture copy comes for "free" during the conversion from the
earlier format to the latter one. So do not bother with copying the
picture before the conversion.

The straight copy is still required however in the case that the video
formats are identical but the display pool is inadequate (too few
pictures, slow memory bus...).
Signed-off-by: Rafaël Carré <funman@videolan.org>

todisplay cannot be NULL there since its two possible values are
checked already.
Signed-off-by: Rafaël Carré <funman@videolan.org>

This reverts commit d8100367.