pkgconf_tuple_add_global
pkgconf_tuple_add_global(client, "pc_sysrootdir", client->sysroot_dir != NULL ? client->sysroot_dir : "/");
pkgconf_tuple_add_global(client, "pc_top_builddir", client->buildroot_dir != NULL ? client->buildroot_dir : "$(top_builddir)");
PKGCONF_API void pkgconf_tuple_add_global(pkgconf_client_t *client, const char *key, const char *value);