adding server support to pgsql.mk?

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

mk/pgsql.buildlink3.mk currently supports choosing a postgresql client
package.

Some programs need an SQL server though, and you can't have
mismatching postgresql client and server versions installed, so I
thought about extending it to allow choosing a server version.

Something like a user-settable variable PGSQL_SERVER, defaulting to
no, which can be set to yes before including pgsql.buildlink3.mk and
then pulls in the corresponding server instead.

Comments?
 Thomas