avcodec/wnv1: Check for width =1

The decoder only outputs pixels for width >1 images, fail early

Fixes: Timeout
Fixes: 48298/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WNV1_fuzzer-6198626319204352

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

libavcodec/wnv1.c

@@ -125,6 +125,9 @@ static av_cold int decode_init(AVCodecContext *avctx)
 {
     static AVOnce init_static_once = AV_ONCE_INIT;
 
+    if (avctx->width <= 1)
+        return AVERROR_INVALIDDATA;
+
     avctx->pix_fmt = AV_PIX_FMT_YUV422P;
 
     ff_thread_once(&init_static_once, wnv1_init_static);