Add missing #include.
Add missing #include.

On non-Windows systems, sys/time.h was pulled in by portability/instr_time.h,
which pulled in time.h. We certainly should include time.h directly, since
we're using time(2), but the indirect include masked the problem on most
platforms.

Andres Freund

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