lavfi: deprecate avfilter_config_links()

It never makes sense for this function to be called by users.

libavfilter/internal.h

@@ -246,6 +246,14 @@ int ff_parse_channel_layout(AVChannelLayout *ret, int *nret, const char *arg,
  */
 void ff_avfilter_link_set_in_status(AVFilterLink *link, int status, int64_t pts);
 
+/**
+ * Negotiate the media format, dimensions, etc of all inputs to a filter.
+ *
+ * @param filter the filter to negotiate the properties for its inputs
+ * @return       zero on successful negotiation
+ */
+int ff_filter_config_links(AVFilterContext *filter);
+
 #define D2TS(d)      (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
 #define TS2D(ts)     ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
 #define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts) * av_q2d(tb))