In particular, no more compiled-in default for PGDATA or LIBDIR. Commands
that need them need either invocation options or environment variables.
PGPORT default is hardcoded as 5432, but overrideable with options or
environment variables.
I'm able to get through a 'make' of the backend with no errors except
the occasional 'might not be initialized error', which is nothing major,
just annoying.
Have a few patches from D'Arcy to incorporate, but am waiting until I can
get a clean compile first, which I'm hoping to have before bed, or sometime
tomorrow.