to certain compile-time options (FUNC_MAX_ARGS, INDEX_MAX_KEYS,
NAMEDATALEN, BLCKSZ, HAVE_INT64_TIMESTAMP). Also added "category",
"short_desc", and "extra_desc" to the pg_settings view. Per recent
discussion here:
http://archives.postgresql.org/pgsql-patches/2003-11/msg00363.php