Fix progress logging when scale factor is large.
Fix progress logging when scale factor is large.

Integer overflow showed minus percent and minus remaining time something like this.
  239300000 of 3800000000 tuples (-48%) done (elapsed 226.86 s, remaining -696.10 s).

ashwinstar/gpdb,lisakowen/gpdb,techdragon/Postgres-XL,oberstet/postgres-xl,Postgres-XL/Postgres-XL,adam8157/gpdb,50wu/gpdb,greenplum-db/gpdb,xinzweb/gpdb,50wu/gpdb,lisakowen/gpdb,adam8157/gpdb,ovr/postgres-xl,greenplum-db/gpdb,50wu/gpdb,jmcatamney/gpdb,yazun/postgres-xl,jmcatamney/gpdb,adam8157/gpdb,ovr/postgres-xl,Postgres-XL/Postgres-XL,pavanvd/postgres-xl,50wu/gpdb,techdragon/Postgres-XL,oberstet/postgres-xl,jmcatamney/gpdb,adam8157/gpdb,xinzweb/gpdb,zeroae/postgres-xl,zeroae/postgres-xl,pavanvd/postgres-xl,zeroae/postgres-xl,xinzweb/gpdb,ashwinstar/gpdb,ovr/postgres-xl,greenplum-db/gpdb,jmcatamney/gpdb,oberstet/postgres-xl,xinzweb/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,Postgres-XL/Postgres-XL,xinzweb/gpdb,ovr/postgres-xl,yazun/postgres-xl,jmcatamney/gpdb,techdragon/Postgres-XL,yazun/postgres-xl,yazun/postgres-xl,zeroae/postgres-xl,greenplum-db/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,lisakowen/gpdb,pavanvd/postgres-xl,greenplum-db/gpdb,oberstet/postgres-xl,adam8157/gpdb,ashwinstar/gpdb,yazun/postgres-xl,ashwinstar/gpdb,Postgres-XL/Postgres-XL,pavanvd/postgres-xl,techdragon/Postgres-XL,techdragon/Postgres-XL,50wu/gpdb,xinzweb/gpdb,lisakowen/gpdb,lisakowen/gpdb,lisakowen/gpdb,pavanvd/postgres-xl,zeroae/postgres-xl,lisakowen/gpdb,Postgres-XL/Postgres-XL,adam8157/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,lisakowen/gpdb,greenplum-db/gpdb,adam8157/gpdb,jmcatamney/gpdb,xinzweb/gpdb,adam8157/gpdb,xinzweb/gpdb,50wu/gpdb,50wu/gpdb,50wu/gpdb,ovr/postgres-xl,oberstet/postgres-xl