pgsql: Fix an oversight in two different recent patches: nodes that

Log Message:
-----------
Fix an oversight in two different recent patches: nodes that support SRFs
in their targetlists had better reset ps_TupFromTlist during ReScan calls.
There's no need to back-patch here since nodeAgg and nodeGroup didn't
even pretend to support SRFs in prior releases.

Modified Files:
--------------
    pgsql/src/backend/executor:
        nodeAgg.c (r1.162 -> r1.163)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeAgg.c?r1=1.162&r2=1.163)
        nodeCtescan.c (r1.1 -> r1.2)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeCtescan.c?r1=1.1&r2=1.2)
        nodeGroup.c (r1.71 -> r1.72)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeGroup.c?r1=1.71&r2=1.72)
        nodeWorktablescan.c (r1.2 -> r1.3)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeWorktablescan.c?r1=1.2&r2=1.3)