minor auth code cleanup

The attached patch makes the following changes:

        - add an assertion to check that the size of the packet
          specified in the protocol is the same amount of data that we
          actually read off the wire.

        - fix some bizarre indentation & grammar mistake in the newly
          added libpq timeout code. Also make some minor cleanup.

        - add a comment noting the intent to replace the fixed size
          user name & database name fields in the protocol with
          variable width ones.

Unless anyone sees a problem, please apply.

Cheers,

Neil

--
Neil Conway <neilc@samurai.com> || PGP Key ID: DB3C29FC