Some VAAPI backends do not support Alpha and chroma keying for subtitles. In that
case print a warning.

Cleanup
- cleanup Render() function
- coding style
- sync with vaapi-x11 branch
- lock access to X11 connection

Rename vlc_va_conn_t::p_display_x11 to vlc_va_conn_t::p_x11.
(cherry picked from commit 60211457)

Conflicts:

	modules/codec/avcodec/vaapi_x11.c

Simplify check for valid surface and chroma.
(cherry picked from commit c4da95eb)

Cleanup no longer needed variables.
(cherry picked from commit df3cbd54)

The video output is now responsible for the surfaces and the pictures. It
needs a special path in modules/codec/avcodec/video.c to make it happen.
This simplifies the code and locking considerably.

Conflicts:

	modules/codec/avcodec/vaapi_x11.c
	modules/codec/avcodec/video.c

The struct picture_pool_configuration_t has 2 functions called Lock and
Unlock, which are called when a picture is taken from the pool and when
a picture is given back to the pool.

The surface i_refcount and i_order counter are no longer sufficient
to tell which surface is free to use.

The function VoutDisplayEventKeyDispatch() missed a return statement.

Force refcount to one in vlc_va_Get().

surface->i_order is not the display order, but more the age of the
surface in use.

Conflicts:

	modules/codec/avcodec/vaapi_x11.c

CreateWindow() returned VLC_SUCCESS, which was interpreted to take the
fail-path instead of checking for NOT VLC_SUCCESS.

Add AC_DEFINE() for HAVE_XCB to actually build the video_output.

Conflicts:
	configure.ac

Fixup: 2c233f96

Use XCB abstraction to Xlib for communication to X11 server. The following
additional changes were needed:

- Split modules/video_output/xcb/xcb_vlc.c in 2
	xcb_vlc.h	 - SHM and PictureResourceAlloc/PictureResourceFree
	xcb_events_vlc.h - matches implementation of modules/video_output/xcb/events.c

The new Peek() function now allocates a block (p_sys->peeked) if the
required size (i_peek) is greater than the size of the playback
segment, and then do a copy of one (or several) segment's data block(s) in it.
In the end, p_sys->peeked might be the concatenation of several segment's data
blocks, but usually it will be NULL.
Signed-off-by: Jean-Paul Saman <jean-paul.saman@m2x.nl>

remove useless prototype
inline vlc identity in the only use case

fix memleak when thread is cancelled

remove FREE_ATT, use do { ... } while(0) for FREE_VALUE
use static const tables for xml handlers
use their size to match handlers with tags
replace {SIMPLE,COMPLEX,UNKNOWN}_CONTENT with a bool

also remove one level of indentation

Cf CVE-2011-0226

Cf CVE-2011-0226

The decoder takes care of that.