Make v4l.c's video_formats constant and static.

Patch by Diego 'Flameeyes' Pettenò flameeyes ¤ gmail ! com

Originally committed as revision 11443 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavdevice/v4l.c

@@ -46,7 +46,7 @@ typedef struct {
     int gb_frame;
 } VideoData;
 
-struct {
+static const struct {
     int palette;
     int depth;
     enum PixelFormat pix_fmt;