Add documentation of the fact that dtrace probes evaluate their parameters even when not active.  Explain how to prevent that with an ENABLED() check.
Add documentation of the fact that dtrace probes evaluate their parameters
even when not active.  Explain how to prevent that with an ENABLED() check.

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