pgsql: Modify processing of DECLARE CURSOR and EXPLAIN so that they can

Log Message:
-----------
Modify processing of DECLARE CURSOR and EXPLAIN so that they can resolve the
types of unspecified parameters when submitted via extended query protocol.
This worked in 8.2 but I had broken it during plancache changes. DECLARE
CURSOR is now treated almost exactly like a plain SELECT through parse
analysis, rewrite, and planning; only just before sending to the executor
do we divert it away to ProcessUtility. This requires a special-case check
in a number of places, but practically all of them were already special-casing
SELECT INTO, so it's not too ugly. (Maybe it would be a good idea to merge
the two by treating IntoClause as a form of utility statement? Not going to
worry about that now, though.) That approach doesn't work for EXPLAIN,
however, so for that I punted and used a klugy solution of running parse
analysis an extra time if under extended query protocol.

Modified Files:
--------------
pgsql/src/backend/commands:
copy.c (r1.282 -> r1.283)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/copy.c.diff?r1=1.282&r2=1.283)
explain.c (r1.161 -> r1.162)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/explain.c.diff?r1=1.161&r2=1.162)
portalcmds.c (r1.64 -> r1.65)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/portalcmds.c.diff?r1=1.64&r2=1.65)
prepare.c (r1.74 -> r1.75)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/prepare.c.diff?r1=1.74&r2=1.75)
pgsql/src/backend/executor:
execMain.c (r1.292 -> r1.293)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/execMain.c.diff?r1=1.292&r2=1.293)
functions.c (r1.115 -> r1.116)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/functions.c.diff?r1=1.115&r2=1.116)
spi.c (r1.178 -> r1.179)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/spi.c.diff?r1=1.178&r2=1.179)
pgsql/src/backend/nodes:
copyfuncs.c (r1.374 -> r1.375)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/copyfuncs.c.diff?r1=1.374&r2=1.375)
equalfuncs.c (r1.305 -> r1.306)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/equalfuncs.c.diff?r1=1.305&r2=1.306)
outfuncs.c (r1.305 -> r1.306)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/outfuncs.c.diff?r1=1.305&r2=1.306)
readfuncs.c (r1.205 -> r1.206)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/readfuncs.c.diff?r1=1.205&r2=1.206)
pgsql/src/backend/optimizer/plan:
planagg.c (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planagg.c.diff?r1=1.31&r2=1.32)
planner.c (r1.217 -> r1.218)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planner.c.diff?r1=1.217&r2=1.218)
pgsql/src/backend/optimizer/prep:
prepjointree.c (r1.47 -> r1.48)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/prep/prepjointree.c.diff?r1=1.47&r2=1.48)
pgsql/src/backend/optimizer/util:
clauses.c (r1.241 -> r1.242)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/clauses.c.diff?r1=1.241&r2=1.242)
pgsql/src/backend/parser:
analyze.c (r1.362 -> r1.363)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/analyze.c.diff?r1=1.362&r2=1.363)
gram.y (r2.590 -> r2.591)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y.diff?r1=2.590&r2=2.591)
parse_clause.c (r1.164 -> r1.165)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_clause.c.diff?r1=1.164&r2=1.165)
parse_expr.c (r1.216 -> r1.217)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_expr.c.diff?r1=1.216&r2=1.217)
parse_type.c (r1.88 -> r1.89)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_type.c.diff?r1=1.88&r2=1.89)
pgsql/src/backend/rewrite:
rewriteDefine.c (r1.119 -> r1.120)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/rewrite/rewriteDefine.c.diff?r1=1.119&r2=1.120)
pgsql/src/backend/tcop:
pquery.c (r1.115 -> r1.116)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/pquery.c.diff?r1=1.115&r2=1.116)
utility.c (r1.278 -> r1.279)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/utility.c.diff?r1=1.278&r2=1.279)
pgsql/src/include/commands:
portalcmds.h (r1.22 -> r1.23)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/portalcmds.h.diff?r1=1.22&r2=1.23)
pgsql/src/include/nodes:
parsenodes.h (r1.347 -> r1.348)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/parsenodes.h.diff?r1=1.347&r2=1.348)
plannodes.h (r1.93 -> r1.94)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/plannodes.h.diff?r1=1.93&r2=1.94)