Initial patch from Doug West.

It fixes support for VC-1 and Theora and Vorbis in avcodec decoder.

This reverts commit 1eefd3dd.
This fixes GLX crashing while requesting an embedded video window.

Conflicts:

	src/video_output/vout_intf.c

Signed-off-by: Rémi Denis-Courmont <rdenis@simphalempin.com>

On Win32, vsnprintf() and vsprintf() are formatting certain things
differently, e.g. "%p". We need to use the same implementation
throughout our vasprintf() replacement.
Signed-off-by: Rémi Denis-Courmont <rdenis@simphalempin.com>

It fixes embed video at start.

Pointed out by Courmish.

It eases security review.

It fixes item name with xpsf playlist (at least).

Otherwise the receiver would -in principle- try to receive RTP on the
next (plus one) even port, whereas the m= line port would be used for
RTCP. We could also pass a=rtcp for the normal even/RTP & odd/RTCP
ports setup, but that can only confuse receivers with no gain.

Note that receivers may not parse the a=rtcp parameter in any case. In
fact, VLC does not parse the a=rtcp field to this day. In any case,
sending RTP to an *even* port is the only safely interoperable option.

Pointed out by Dnumgis.

Without it, input_ressource_HoldVout and vout windows request could deadlock.