avcodec/mpeg12dec: Set dimensions in mpeg1_decode_sequence() only in absence of errors

Fixes assertion failure
Fixes: 56dcafde14a8397161bb61a16c511179/signal_sigabrt_7ffff6ac8cc9_686_cov_1897408623_microsoft_new_way_to_shove_mpeg2_in_asf.dvr_ms

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/mpeg12dec.c

@@ -2179,8 +2179,6 @@ static int mpeg1_decode_sequence(AVCodecContext *avctx,
     if (check_marker(&s->gb, "in sequence header") == 0) {
         return AVERROR_INVALIDDATA;
     }
-    s->width  = width;
-    s->height = height;
 
     s->avctx->rc_buffer_size = get_bits(&s->gb, 10) * 1024 * 16;
     skip_bits(&s->gb, 1);
@@ -2212,6 +2210,9 @@ static int mpeg1_decode_sequence(AVCodecContext *avctx,
         return AVERROR_INVALIDDATA;
     }
 
+    s->width  = width;
+    s->height = height;
+
     /* We set MPEG-2 parameters so that it emulates MPEG-1. */
     s->progressive_sequence = 1;
     s->progressive_frame    = 1;