lavfi: drop now unused shorthand field from AVFilter.

libavfilter/avfilter.c

@@ -606,7 +606,7 @@ void avfilter_free(AVFilterContext *filter)
         avfilter_link_free(&link);
     }
 
-    if (filter->filter->priv_class || filter->filter->shorthand)
+    if (filter->filter->priv_class)
         av_opt_free(filter->priv);
 
     av_freep(&filter->name);

libavfilter/avfilter.h

@@ -518,15 +518,6 @@ typedef struct AVFilter {
      * used for providing binary data.
      */
     int (*init_opaque)(AVFilterContext *ctx, void *opaque);
-
-    /**
-     * Shorthand syntax for init arguments.
-     * If this field is set (even to an empty list), just before init the
-     * private class will be set and the arguments string will be parsed
-     * using av_opt_set_from_string() with "=" and ":" delimiters, and
-     * av_opt_free() will be called just after uninit.
-     */
-    const char *const *shorthand;
 } AVFilter;
 
 /** An instance of a filter */