BUG #13782: gss auth with libpq does not include realm by default

The following bug has been logged on the website:

Bug reference:      13782
Logged by:          John Kew
Email address:      jkew@tableau.com
PostgreSQL version: 9.5beta1
Operating system:   Windows 7
Description:

Recently a change was made to set include_realm=1 by default. This is
sensible.

Clients and drivers using libpq, however, default to sending just the
username w/o the realm, leading to a gss username error in these
configurations.

You can force psql and postgres-odbc to use a specific username which
includes the realm; but it would be useful if libpq had the same default as
the server and sent the current realm by default e.g: joe@realm.com.

Seems like a minor thing; but it means you can share the same connection
string configuration between users for when postgres is configured the
recommended way.