collectd: add reload and service trigger

Signed-off-by: Florian Eckert <fe@dev.tdt.de>
(cherry-picked for 19.07)
Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>

utils/collectd/files/collectd.init

@@ -333,6 +333,11 @@ process_config() {
 	config_foreach process_plugins plugin
 }
 
+service_triggers()
+{
+	procd_add_reload_trigger "collectd"
+}
+
 start_service() {
 	process_config
 
@@ -345,3 +350,7 @@ start_service() {
 	procd_set_param respawn
 	procd_close_instance
 }
+
+reload_service() {
+	restart "$@"
+}