avfilter/vf_bwdif: fix heap-buffer overflow

Fixes #8261

(cherry picked from commit 8c3166e1

)
Signed-off-by: James Almer <jamrial@gmail.com>

libavfilter/vf_bwdif.c

@@ -505,8 +505,8 @@ static int config_props(AVFilterLink *link)
     if(s->mode&1)
         link->frame_rate = av_mul_q(link->src->inputs[0]->frame_rate, (AVRational){2,1});
 
-    if (link->w < 3 || link->h < 3) {
-        av_log(ctx, AV_LOG_ERROR, "Video of less than 3 columns or lines is not supported\n");
+    if (link->w < 3 || link->h < 4) {
+        av_log(ctx, AV_LOG_ERROR, "Video of less than 3 columns or 4 lines is not supported\n");
         return AVERROR(EINVAL);
     }