avs: check ff_set_dimensions return value

CC: libav-stable@libav.org
Bug-Id: CID 1135738
(cherry picked from commit c7384664ba0cbb12d882effafbc6d321ae706cff)
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavcodec/avs.c

@@ -165,9 +165,8 @@ static av_cold int avs_decode_init(AVCodecContext * avctx)
         return AVERROR(ENOMEM);
 
     avctx->pix_fmt = AV_PIX_FMT_PAL8;
-    ff_set_dimensions(avctx, 318, 198);
 
-    return 0;
+    return ff_set_dimensions(avctx, 318, 198);
 }
 
 static av_cold int avs_decode_end(AVCodecContext *avctx)