Thread: pgsql: Remove useless ps_OuterTupleSlot field from PlanState.

Log Message:
-----------
Remove useless ps_OuterTupleSlot field from PlanState.  I suppose this was
used long ago, but in the current code the ecxt_outertuple field of
ExprContext is doing all the work.  Spotted by Ran Tang.

Modified Files:
--------------
    pgsql/src/backend/executor:
        nodeHashjoin.c (r1.95 -> r1.96)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeHashjoin.c?r1=1.95&r2=1.96)
        nodeNestloop.c (r1.48 -> r1.49)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeNestloop.c?r1=1.48&r2=1.49)
    pgsql/src/include/nodes:
        execnodes.h (r1.190 -> r1.191)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/execnodes.h?r1=1.190&r2=1.191)