ffv1: align slice context struct

Author: cyanreg

libavcodec/ffv1.h

@@ -34,6 +34,7 @@
 #include "progressframe.h"
 #include "put_bits.h"
 #include "rangecoder.h"
+#include "libavutil/mem_internal.h"
 
 #ifdef __INTEL_COMPILER
 #undef av_flatten
@@ -69,7 +70,7 @@ typedef struct PlaneContext {
 
 #define MAX_SLICES 1024
 
-typedef struct FFV1SliceContext {
+DECLARE_ALIGNED(16, typedef, struct) {
     PlaneContext plane[MAX_PLANES];
 
     PutBitContext pb;