Fix crash caused by NULL lookup when reporting IP address of failed libpq connection, per report from Magnus.  This happens only on GIT master and only on Win32 because that is the platform where "" maps to an IP address (localhost).
Fix crash caused by NULL lookup when reporting IP address of failed
libpq connection, per report from Magnus.  This happens only on GIT
master and only on Win32 because that is the platform where "" maps to
an IP address (localhost).

arcivanov/postgres-xl,yazun/postgres-xl,jmcatamney/gpdb,pavanvd/postgres-xl,ashwinstar/gpdb,techdragon/Postgres-XL,oberstet/postgres-xl,zeroae/postgres-xl,postmind-net/postgres-xl,tpostgres-projects/tPostgres,tpostgres-projects/tPostgres,adam8157/gpdb,adam8157/gpdb,xinzweb/gpdb,lisakowen/gpdb,50wu/gpdb,arcivanov/postgres-xl,greenplum-db/gpdb,tpostgres-projects/tPostgres,arcivanov/postgres-xl,50wu/gpdb,Postgres-XL/Postgres-XL,50wu/gpdb,ovr/postgres-xl,kmjungersen/PostgresXL,50wu/gpdb,arcivanov/postgres-xl,greenplum-db/gpdb,kmjungersen/PostgresXL,postmind-net/postgres-xl,adam8157/gpdb,lisakowen/gpdb,techdragon/Postgres-XL,techdragon/Postgres-XL,jmcatamney/gpdb,postmind-net/postgres-xl,tpostgres-projects/tPostgres,xinzweb/gpdb,xinzweb/gpdb,snaga/postgres-xl,Postgres-XL/Postgres-XL,ashwinstar/gpdb,zeroae/postgres-xl,tpostgres-projects/tPostgres,pavanvd/postgres-xl,xinzweb/gpdb,adam8157/gpdb,zeroae/postgres-xl,Postgres-XL/Postgres-XL,snaga/postgres-xl,techdragon/Postgres-XL,adam8157/gpdb,xinzweb/gpdb,adam8157/gpdb,pavanvd/postgres-xl,yazun/postgres-xl,adam8157/gpdb,50wu/gpdb,greenplum-db/gpdb,ovr/postgres-xl,yazun/postgres-xl,yazun/postgres-xl,greenplum-db/gpdb,pavanvd/postgres-xl,jmcatamney/gpdb,kmjungersen/PostgresXL,yazun/postgres-xl,greenplum-db/gpdb,greenplum-db/gpdb,oberstet/postgres-xl,xinzweb/gpdb,xinzweb/gpdb,Postgres-XL/Postgres-XL,arcivanov/postgres-xl,ashwinstar/gpdb,ashwinstar/gpdb,lisakowen/gpdb,zeroae/postgres-xl,ashwinstar/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,snaga/postgres-xl,adam8157/gpdb,greenplum-db/gpdb,kmjungersen/PostgresXL,jmcatamney/gpdb,lisakowen/gpdb,pavanvd/postgres-xl,Postgres-XL/Postgres-XL,snaga/postgres-xl,jmcatamney/gpdb,oberstet/postgres-xl,xinzweb/gpdb,zeroae/postgres-xl,lisakowen/gpdb,50wu/gpdb,ovr/postgres-xl,arcivanov/postgres-xl,ashwinstar/gpdb,jmcatamney/gpdb,oberstet/postgres-xl,ashwinstar/gpdb,snaga/postgres-xl,50wu/gpdb,postmind-net/postgres-xl,oberstet/postgres-xl,lisakowen/gpdb,jmcatamney/gpdb,postmind-net/postgres-xl,greenplum-db/gpdb,ovr/postgres-xl,lisakowen/gpdb,kmjungersen/PostgresXL,lisakowen/gpdb,50wu/gpdb,techdragon/Postgres-XL,ovr/postgres-xl