Add a hack requested by the JDBC driver writers: when a function's

argument list contains parameter symbols ($n) declared as type VOID,
discard these arguments.  This allows the driver to avoid renumbering
mixed IN and OUT argument placeholders (the JDBC syntax involves writing
? for both IN and OUT parameters, but on the server side we don't think
that OUT parameters are arguments).  This doesn't break any currently-
useful cases since VOID is not used as an input argument type.