Fix "initialization from incompatible pointer type" warning in rv34.

Patch by Eli Friedman (at gmail).

Originally committed as revision 23897 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/rv34.c

@@ -1142,7 +1142,7 @@ static int rv34_set_deblock_coef(RV34DecContext *r)
     MpegEncContext *s = &r->s;
     int hmvmask = 0, vmvmask = 0, i, j;
     int midx = s->mb_x * 2 + s->mb_y * 2 * s->b8_stride;
-    int16_t (*motion_val)[2] = s->current_picture_ptr->motion_val[0][midx];
+    int16_t (*motion_val)[2] = &s->current_picture_ptr->motion_val[0][midx];
     for(j = 0; j < 16; j += 8){
         for(i = 0; i < 2; i++){
             if(is_mv_diff_gt_3(motion_val + i, 1))