DERBY-6314: Upgrade from 10.10 fails with ClassCastException

Make ExecRowBuilder implement the Formatable interface so that any
Formatable instances referenced from its fields are stored using
Formatable logic instead of Serializable logic.

Add type checking in FormatIdInputStream's error handlers to prevent
the underlying exception from being shadowed by a ClassCastException
under certain circumstances.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1517761 13f79535-47bb-0310-9956-ffa450edef68