pgsql: Ensure that the result tuple of an EvalPlanQual cycle gets

Log Message:
-----------
Ensure that the result tuple of an EvalPlanQual cycle gets materialized
before we zap the input tuple.  Otherwise, pass-by-reference columns of
the result slot are likely to contain just references to the input
tuple, leading to big trouble if the pfree'd space is reused.  Per
trouble report from Jaime Casanova.  This is a new bug in the recent
rewrite of EvalPlanQual, so nothing to back-patch.

Modified Files:
--------------
    pgsql/src/backend/executor:
        execMain.c (r1.336 -> r1.337)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/execMain.c?r1=1.336&r2=1.337)