Make the pix_fmts var in query_formats() static const.

Originally committed as revision 20343 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavfilter/vf_crop.c

@@ -37,7 +37,7 @@ typedef struct {
 
 static int query_formats(AVFilterContext *ctx)
 {
-    enum PixelFormat pix_fmts[] = {
+    static const enum PixelFormat pix_fmts[] = {
         PIX_FMT_RGB48BE,      PIX_FMT_RGB48LE,
         PIX_FMT_ARGB,         PIX_FMT_RGBA,
         PIX_FMT_ABGR,         PIX_FMT_BGRA,