lavfi/concat: switch to an AVOptions-based system.

doc/filters.texi

@@ -6937,7 +6937,8 @@ The filter works on segments of synchronized video and audio streams. All
 segments must have the same number of streams of each type, and that will
 also be the number of streams at output.
 
-The filter accepts the following named parameters:
+The filter accepts the following options:
+
 @table @option
 
 @item n

libavfilter/avf_concat.c

@@ -409,8 +409,6 @@ static av_cold void uninit(AVFilterContext *ctx)
     av_free(cat->in);
 }
 
-static const char *const shorthand[] = { NULL };
-
 AVFilter avfilter_avf_concat = {
     .name          = "concat",
     .description   = NULL_IF_CONFIG_SMALL("Concatenate audio and video streams."),
@@ -421,5 +419,4 @@ AVFilter avfilter_avf_concat = {
     .inputs        = NULL,
     .outputs       = NULL,
     .priv_class    = &concat_class,
-    .shorthand     = shorthand,
 };

libavfilter/avfilter.c

@@ -697,6 +697,7 @@ int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque
         !strcmp(filter->filter->name,  "channelsplit") ||
         !strcmp(filter->filter->name,  "color"     ) ||
         !strcmp(filter->filter->name,  "colormatrix") ||
+        !strcmp(filter->filter->name,  "concat"    ) ||
         !strcmp(filter->filter->name,  "crop"      ) ||
         !strcmp(filter->filter->name,  "cropdetect") ||
         !strcmp(filter->filter->name,  "curves"    ) ||