Add aggregate_with_argtypes and use it consistently
Add aggregate_with_argtypes and use it consistently

This works like function_with_argtypes, but aggregates allow slightly
different arguments.

Reviewed-by: Alvaro Herrera <3c84f0de6f8a0f296d36cdd9f57fa166641c96b1@2ndquadrant.com>
Reviewed-by: Tom Lane <ffeaa947aef224da9ba99b6a18bdd74288df0e3e@sss.pgh.pa.us>

xinzweb/gpdb,greenplum-db/gpdb,adam8157/gpdb,50wu/gpdb,lisakowen/gpdb,lisakowen/gpdb,greenplum-db/gpdb,xinzweb/gpdb,greenplum-db/gpdb,xinzweb/gpdb,xinzweb/gpdb,greenplum-db/gpdb,adam8157/gpdb,50wu/gpdb,adam8157/gpdb,50wu/gpdb,greenplum-db/gpdb,adam8157/gpdb,lisakowen/gpdb,greenplum-db/gpdb,lisakowen/gpdb,lisakowen/gpdb,adam8157/gpdb,xinzweb/gpdb,50wu/gpdb,xinzweb/gpdb,xinzweb/gpdb,greenplum-db/gpdb,lisakowen/gpdb,adam8157/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,50wu/gpdb,50wu/gpdb,greenplum-db/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb