pkgconf_path_build_from_environ
pkgconf_path_build_from_environ("PKG_CONFIG_SYSTEM_LIBRARY_PATH", NULL, &client->filter_libdirs, false);
pkgconf_path_build_from_environ("PKG_CONFIG_SYSTEM_INCLUDE_PATH", NULL, &client->filter_includedirs, false);
pkgconf_path_build_from_environ("BELIBRARIES", NULL, &client->filter_libdirs, false);
pkgconf_path_build_from_environ("LIBRARY_PATH", NULL, &client->filter_libdirs, false);
pkgconf_path_build_from_environ("CPATH", NULL, &client->filter_includedirs, false);
pkgconf_path_build_from_environ("C_INCLUDE_PATH", NULL, &client->filter_includedirs, false);
pkgconf_path_build_from_environ("CPLUS_INCLUDE_PATH", NULL, &client->filter_includedirs, false);
pkgconf_path_build_from_environ("OBJC_INCLUDE_PATH", NULL, &client->filter_includedirs, false);
pkgconf_path_build_from_environ("INCLUDE", NULL, &client->filter_includedirs, false);
pkgconf_path_build_from_environ("PKG_CONFIG_PATH", NULL, &client->dir_list, true);
(void) pkgconf_path_build_from_environ("PKG_CONFIG_LIBDIR", NULL, &dir_list, true);
PKGCONF_API size_t pkgconf_path_build_from_environ(const char *envvarname, const char *fallback, pkgconf_list_t *dirlist, bool filter);
pkgconf_path_build_from_environ("XDG_DATA_DIRS", "/usr/local/share" PKG_CONFIG_PATH_SEP_S "/usr/share", &plist, true);