Backport upstream comment updates
Backport upstream comment updates

commit 96f990e23bae0559ede95e94340d2fc918dfde44
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date:   Wed Jul 13 20:23:09 2011 -0400

    Update some comments to clarify who does what in targetlist creation.

    No code changes; just avoid blaming query_planner for things it doesn't
    really do.

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