curl: set INTERLEAVEDATA too

As otherwise the callback could be called with a NULL pointer when RTSP
data is provided.

src/tool_operate.c

@@ -800,6 +800,7 @@ static CURLcode operate_do(struct GlobalConfig *global,
 
         /* where to store */
         my_setopt(curl, CURLOPT_WRITEDATA, &outs);
+        my_setopt(curl, CURLOPT_INTERLEAVEDATA, &outs);
         if(metalink || !config->use_metalink)
           /* what call to write */
           my_setopt(curl, CURLOPT_WRITEFUNCTION, tool_write_cb);