Repair bugs in declarations of routines to add timestamptz and interval.

Repair bugs in declarations of routines to add timestamptz and interval.
 Thanks to Bruce for spotting it and Tom Lane for diagnosing it.
Since horology test output is changing anyway, add some date/time input
 tests to horology.sql. Some of these should move to the tests for the
 individual data types, and we perhaps should add an entire new test
 for "timezone" to allow manipulating the current time zone without
 risking damage to the results of other tests.