pgsql: Fix the mechanism for reporting the original table OID and column

Log Message:
-----------
Fix the mechanism for reporting the original table OID and column number
of columns of a query result so that it can "see through" cursors and
prepared statements.  Per gripe a couple months back from John DeSoi.

Modified Files:
--------------
    pgsql/src/backend/access/common:
        printtup.c (r1.90 -> r1.91)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/common/printtup.c.diff?r1=1.90&r2=1.91)
    pgsql/src/backend/commands:
        prepare.c (r1.39 -> r1.40)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/prepare.c.diff?r1=1.39&r2=1.40)
    pgsql/src/backend/tcop:
        postgres.c (r1.449 -> r1.450)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c.diff?r1=1.449&r2=1.450)
        pquery.c (r1.93 -> r1.94)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/pquery.c.diff?r1=1.93&r2=1.94)
    pgsql/src/include/commands:
        prepare.h (r1.13 -> r1.14)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/prepare.h.diff?r1=1.13&r2=1.14)
    pgsql/src/include/tcop:
        pquery.h (r1.34 -> r1.35)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/tcop/pquery.h.diff?r1=1.34&r2=1.35)