avcodec/dnxhdenc: Fix alignment of edge_buf*

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/dnxhdenc.h

@@ -71,8 +71,8 @@ typedef struct DNXHDEncContext {
     int intra_quant_bias;
 
     DECLARE_ALIGNED(16, int16_t, blocks)[8][64];
-    uint8_t edge_buf_y[256];
-    uint8_t edge_buf_uv[2][128];
+    DECLARE_ALIGNED(16, uint8_t, edge_buf_y)[256];
+    DECLARE_ALIGNED(16, uint8_t, edge_buf_uv)[2][128];
 
     int      (*qmatrix_c)     [64];
     int      (*qmatrix_l)     [64];