cmdutils: print slice threading flag in -filters.

cmdutils.c

@@ -1454,7 +1454,8 @@ int show_filters(void *optctx, const char *opt, const char *arg)
     const AVFilterPad *pad;
 
     printf("Filters:\n"
-           "  T = Timeline support\n"
+           "  T. = Timeline support\n"
+           "  .S = Slice threading\n"
            "  A = Audio input/output\n"
            "  V = Video input/output\n"
            "  N = Dynamic number and/or type of input/output\n"
@@ -1478,7 +1479,9 @@ int show_filters(void *optctx, const char *opt, const char *arg)
                                   ( i && (filter->flags & AVFILTER_FLAG_DYNAMIC_OUTPUTS))) ? 'N' : '|';
         }
         *descr_cur = 0;
-        printf(" %c %-16s %-10s %s\n", filter->flags & AVFILTER_FLAG_SUPPORT_TIMELINE ? 'T' : '.',
+        printf(" %c%c %-16s %-10s %s\n",
+               filter->flags & AVFILTER_FLAG_SUPPORT_TIMELINE ? 'T' : '.',
+               filter->flags & AVFILTER_FLAG_SLICE_THREADS    ? 'S' : '.',
                filter->name, descr, filter->description);
     }
 #endif