aupg - aupg_src: Fixed incompatibility with PostgreSQL 8.3's new

Log Message:
-----------
Fixed incompatibility with PostgreSQL 8.3's new transaction id model.

WARNING!

NOTE that the change in storage type from int to bigint for transaction ids
means that this is not a compatible upgrade from previous versions of AuPG.

It should be possible to convert from ints as stored in old audit tables and
trust graphs, to the new bigints, but I have not done so in any automated way.

Modified Files:
--------------
    aupg_src/sql:
        _test_setup.sql (r1.3 -> r1.4)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/aupg/aupg_src/sql/_test_setup.sql.diff?r1=1.3&r2=1.4)
        _test_takedown.sql (r1.3 -> r1.4)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/aupg/aupg_src/sql/_test_takedown.sql.diff?r1=1.3&r2=1.4)
        audit_infrastructure.sql (r1.17 -> r1.18)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/aupg/aupg_src/sql/audit_infrastructure.sql.diff?r1=1.17&r2=1.18)