avfilter/internal: Don't include video.h

internal.h does not depend on video.h (and should not depend on it)
and therefore should not include video.h at all; instead all users
of video.h should include it directly.

Doing so also avoids unnecessary video.h inclusions in files that
don't need it, like most audio filters.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavfilter/vf_extractplanes.c

@@ -29,6 +29,7 @@
 #include "drawutils.h"
 #include "filters.h"
 #include "internal.h"
+#include "video.h"
 
 #define PLANE_R 0x01
 #define PLANE_G 0x02