pkgconf_scan_all
pkgconf_scan_all(&pkg_client, NULL, print_list_entry);
pkgconf_scan_all(&pkg_client, NULL, print_package_entry);
PKGCONF_API pkgconf_pkg_t *pkgconf_scan_all(pkgconf_client_t *client, void *ptr, pkgconf_pkg_iteration_func_t func);
pkg = pkgconf_scan_all(client, &ctx, (pkgconf_pkg_iteration_func_t) pkgconf_pkg_scan_provides_entry);