Import postgresql9[1-5]-contrib packages. These supersede the
previous handful of packages like -datatypes or -dblink. They
contain all of the contrib subtree, matching what similar packages
carry in e.g. FreeBSD ports or what PostgreSQL users generally
expect.

This subtree contains porting tools, analysis utilities, and
plug-in features that are not part of the core PostgreSQL system,
mainly because they address a limited audience or are too
experimental to be part of the main source tree. This does not
preclude their usefulness.

(fhajny)