avcodec/mpeg12enc: increase declared size of block function argument

Fixes CID1047236
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mpeg12enc.c

@@ -683,7 +683,7 @@ next_coef:
 }
 
 static av_always_inline void mpeg1_encode_mb_internal(MpegEncContext *s,
-                                                      int16_t block[6][64],
+                                                      int16_t block[8][64],
                                                       int motion_x, int motion_y,
                                                       int mb_block_count)
 {
@@ -960,7 +960,7 @@ static av_always_inline void mpeg1_encode_mb_internal(MpegEncContext *s,
     }
 }
 
-void ff_mpeg1_encode_mb(MpegEncContext *s, int16_t block[6][64],
+void ff_mpeg1_encode_mb(MpegEncContext *s, int16_t block[8][64],
                         int motion_x, int motion_y)
 {
     if (s->chroma_format == CHROMA_420)