pgsql: Simplify ParamListInfo data structure to support only numbered

Log Message:
-----------
Simplify ParamListInfo data structure to support only numbered parameters,
not named ones, and replace linear searches of the list with array indexing.
The named-parameter support has been dead code for many years anyway,
and recent profiling suggests that the searching was costing a noticeable
amount of performance for complex queries.

Modified Files:
--------------
pgsql/src/backend/commands:
prepare.c (r1.49 -> r1.50)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/prepare.c.diff?r1=1.49&r2=1.50)
pgsql/src/backend/executor:
execQual.c (r1.189 -> r1.190)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/execQual.c.diff?r1=1.189&r2=1.190)
functions.c (r1.101 -> r1.102)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/functions.c.diff?r1=1.101&r2=1.102)
spi.c (r1.150 -> r1.151)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/spi.c.diff?r1=1.150&r2=1.151)
pgsql/src/backend/nodes:
copyfuncs.c (r1.333 -> r1.334)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/copyfuncs.c.diff?r1=1.333&r2=1.334)
equalfuncs.c (r1.269 -> r1.270)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/equalfuncs.c.diff?r1=1.269&r2=1.270)
outfuncs.c (r1.272 -> r1.273)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/outfuncs.c.diff?r1=1.272&r2=1.273)
params.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/params.c.diff?r1=1.5&r2=1.6)
readfuncs.c (r1.187 -> r1.188)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/readfuncs.c.diff?r1=1.187&r2=1.188)
pgsql/src/backend/optimizer/plan:
subselect.c (r1.104 -> r1.105)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/subselect.c.diff?r1=1.104&r2=1.105)
pgsql/src/backend/optimizer/util:
clauses.c (r1.210 -> r1.211)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/clauses.c.diff?r1=1.210&r2=1.211)
pgsql/src/backend/parser:
analyze.c (r1.332 -> r1.333)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/analyze.c.diff?r1=1.332&r2=1.333)
parse_coerce.c (r2.137 -> r2.138)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_coerce.c.diff?r1=2.137&r2=2.138)
parse_expr.c (r1.191 -> r1.192)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_expr.c.diff?r1=1.191&r2=1.192)
pgsql/src/backend/tcop:
postgres.c (r1.484 -> r1.485)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c.diff?r1=1.484&r2=1.485)
pgsql/src/backend/utils/adt:
ruleutils.c (r1.219 -> r1.220)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/ruleutils.c.diff?r1=1.219&r2=1.220)
pgsql/src/include/catalog:
catversion.h (r1.322 -> r1.323)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.322&r2=1.323)
pgsql/src/include/nodes:
params.h (r1.30 -> r1.31)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/params.h.diff?r1=1.30&r2=1.31)
primnodes.h (r1.112 -> r1.113)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/primnodes.h.diff?r1=1.112&r2=1.113)
pgsql/src/pl/plpgsql/src:
pl_exec.c (r1.163 -> r1.164)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_exec.c.diff?r1=1.163&r2=1.164)