lavfi: set the link hwframes context before configuring the dst input

The destination filter might expect the hw frames context to be already
set (this is the case e.g. for hwdownload).

libavfilter/avfilter.c

@@ -211,14 +211,6 @@ int avfilter_config_links(AVFilterContext *filter)
                 }
             }
 
-            if ((config_link = link->dstpad->config_props))
-                if ((ret = config_link(link)) < 0) {
-                    av_log(link->dst, AV_LOG_ERROR,
-                           "Failed to configure input pad on %s\n",
-                           link->dst->name);
-                    return ret;
-                }
-
             if (link->src->nb_inputs && link->src->inputs[0]->hw_frames_ctx &&
                 !link->hw_frames_ctx) {
                 AVHWFramesContext *input_ctx = (AVHWFramesContext*)link->src->inputs[0]->hw_frames_ctx->data;
@@ -230,6 +222,14 @@ int avfilter_config_links(AVFilterContext *filter)
                 }
             }
 
+            if ((config_link = link->dstpad->config_props))
+                if ((ret = config_link(link)) < 0) {
+                    av_log(link->dst, AV_LOG_ERROR,
+                           "Failed to configure input pad on %s\n",
+                           link->dst->name);
+                    return ret;
+                }
+
             link->init_state = AVLINK_INIT;
         }
     }