add ucimap_free_section to the api

ucimap.c

@@ -136,7 +136,7 @@ ucimap_add_alloc(struct ucimap_section_data *sd, void *ptr)
 	a->data.ptr = ptr;
 }
 
-static void
+void
 ucimap_free_section(struct uci_map *map, struct ucimap_section_data *sd)
 {
 	void *section;

ucimap.h

@@ -205,5 +205,6 @@ extern void ucimap_set_changed(struct ucimap_section_data *sd, void *field);
 extern int ucimap_store_section(struct uci_map *map, struct uci_package *p, struct ucimap_section_data *sd);
 extern void ucimap_parse(struct uci_map *map, struct uci_package *pkg);
 extern int ucimap_parse_section(struct uci_map *map, struct uci_sectionmap *sm, struct ucimap_section_data *sd, struct uci_section *s);
+extern void ucimap_free_section(struct uci_map *map, struct ucimap_section_data *sd);
 
 #endif