avcodec/pictordec: Fix logic error

Fixes: 559/clusterfuzz-testcase-6424225917173760

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

libavcodec/pictordec.c

@@ -142,7 +142,7 @@ static int decode_frame(AVCodecContext *avctx,
 
     if (av_image_check_size(s->width, s->height, 0, avctx) < 0)
         return -1;
-    if (s->width != avctx->width && s->height != avctx->height) {
+    if (s->width != avctx->width || s->height != avctx->height) {
         ret = ff_set_dimensions(avctx, s->width, s->height);
         if (ret < 0)
             return ret;