avcodec/rtv1: fix undefined FFALIGN

Fixes: signed integer overflow: 2147483647 + 4 cannot be represented in type 'int'
Fixes: 62285/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_RTV1_fuzzer-6324303861514240

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/rtv1.c

@@ -113,6 +113,8 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *p,
 
     width = bytestream2_get_le32(&gb);
     height = bytestream2_get_le32(&gb);
+    if (width > INT_MAX-4U || height > INT_MAX-4U)
+        return AVERROR_INVALIDDATA;
     ret = ff_set_dimensions(avctx, FFALIGN(width, 4), FFALIGN(height, 4));
     if (ret < 0)
         return ret;