Fixes to make ext/libcaca compile.

Fixes to make ext/libcaca compile.

Original commit message from CVS:
* configure.ac:
* ext/Makefile.am: Fixes to make ext/libcaca compile.
* ext/divx/gstdivxdec.c:
* ext/gdk_pixbuf/gstgdkpixbuf.c: (gst_gdk_pixbuf_sink_link),
(gst_gdk_pixbuf_init), (gst_gdk_pixbuf_chain): Make gdkpixbufdec
handle images that span multiple buffers.  Now work with both
filesrc ! gdkpixbufdec and qtdemux ! gdkpixbufdec.
* ext/gdk_pixbuf/gstgdkpixbuf.h:
* ext/libcaca/gstcacasink.h: Fixes needed due to recent
video/video.h changes
* ext/xvid/gstxvid.c: (gst_xvid_csp_to_caps): same
* sys/v4l/gstv4lmjpegsrc.c: (gst_v4lmjpegsrc_get),
(gst_v4lmjpegsrc_buffer_free): Use buffer free function instead
of GstData free function.
* sys/v4l/gstv4lsrc.c: (gst_v4lsrc_get), (gst_v4lsrc_buffer_free):
same.