This isn't fully tested as yet, in particular I'm not sure that the
"foo--unpackaged--1.0.sql" scripts are OK. But it's time to get some
buildfarm cycles on it.
sepgsql is not converted to an extension, mainly because it seems to
require a very nonstandard installation process.
Dimitri Fontaine and Tom Lane
installations whose pg_config program does not appear first in the PATH.
Per gripe from Eddie Stanley and subsequent discussions with Fabien Coelho
and others.
