gpsegwalrep.py: Fix for clusterstart
gpsegwalrep.py: Fix for clusterstart

Ignore segments not marked as up for clusterstart operation.

Author: Xin Zhang <80ac6425c128040c27b3c6077c824bc26222f5e7@pivotal.io>
Author: Asim R P <24f343109504afa210657d296a0873118cbd2b97@pivotal.io>

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