pg_dump: improve big-O of partition dependency generation
pg_dump: improve big-O of partition dependency generation

We were doing a linear search through the list of tables to find the
correct OID. That's what findTableByOid() is for -- it does a binary
search on the sorted list of tables -- so use it instead.

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