avcodec/aic: unbreak decoding of files with slice_width != 16

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/aic.c

@@ -449,7 +449,7 @@ static av_cold int aic_decode_init(AVCodecContext *avctx)
 
     ctx->num_x_slices = (ctx->mb_width + 15) >> 4;
     ctx->slice_width  = 16;
-    for (i = 1; i < 32; i++) {
+    for (i = 1; i < ctx->mb_width; i++) {
         if (!(ctx->mb_width % i) && (ctx->mb_width / i <= 32)) {
             ctx->slice_width  = ctx->mb_width / i;
             ctx->num_x_slices = i;