pgsql: Add a new tuplestore API function, tuplestore_putvalues().

Log Message:
-----------
Add a new tuplestore API function, tuplestore_putvalues(). This is
identical to tuplestore_puttuple(), except it operates on arrays of
Datums + nulls rather than a fully-formed HeapTuple. In several places
that use the tuplestore API, this means we can avoid creating a
HeapTuple altogether, saving a copy.

Modified Files:
--------------
pgsql/src/backend/commands:
prepare.c (r1.80 -> r1.81)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/prepare.c?r1=1.80&r2=1.81)
pgsql/src/backend/executor:
execQual.c (r1.226 -> r1.227)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/execQual.c?r1=1.226&r2=1.227)
pgsql/src/backend/utils/mmgr:
portalmem.c (r1.106 -> r1.107)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/mmgr/portalmem.c?r1=1.106&r2=1.107)
pgsql/src/backend/utils/sort:
tuplestore.c (r1.37 -> r1.38)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/sort/tuplestore.c?r1=1.37&r2=1.38)
pgsql/src/include/utils:
tuplestore.h (r1.22 -> r1.23)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/tuplestore.h?r1=1.22&r2=1.23)
pgsql/src/pl/plperl:
plperl.c (r1.136 -> r1.137)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/plperl.c?r1=1.136&r2=1.137)
pgsql/src/pl/plpgsql/src:
pl_exec.c (r1.202 -> r1.203)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_exec.c?r1=1.202&r2=1.203)