pgsql: Support "variadic" functions, which can accept a variable number

Log Message:
-----------
Support "variadic" functions, which can accept a variable number of arguments
so long as all the trailing arguments are of the same (non-array) type.
The function receives them as a single array argument (which is why they
have to all be the same type).

It might be useful to extend this facility to aggregates, but this patch
doesn't do that.

This patch imposes a noticeable slowdown on function lookup --- a follow-on
patch will fix that by adding a redundant column to pg_proc.

Pavel Stehule

Modified Files:
--------------
pgsql/doc/src/sgml:
catalogs.sgml (r2.168 -> r2.169)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/catalogs.sgml?r1=2.168&r2=2.169)
extend.sgml (r1.36 -> r1.37)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/extend.sgml?r1=1.36&r2=1.37)
plpgsql.sgml (r1.131 -> r1.132)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/plpgsql.sgml?r1=1.131&r2=1.132)
typeconv.sgml (r1.54 -> r1.55)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/typeconv.sgml?r1=1.54&r2=1.55)
xfunc.sgml (r1.130 -> r1.131)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/xfunc.sgml?r1=1.130&r2=1.131)
pgsql/doc/src/sgml/ref:
alter_function.sgml (r1.15 -> r1.16)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_function.sgml?r1=1.15&r2=1.16)
comment.sgml (r1.36 -> r1.37)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/comment.sgml?r1=1.36&r2=1.37)
create_function.sgml (r1.78 -> r1.79)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_function.sgml?r1=1.78&r2=1.79)
drop_function.sgml (r1.33 -> r1.34)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/drop_function.sgml?r1=1.33&r2=1.34)
pgsql/src/backend/catalog:
information_schema.sql (r1.43 -> r1.44)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/information_schema.sql?r1=1.43&r2=1.44)
namespace.c (r1.107 -> r1.108)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/namespace.c?r1=1.107&r2=1.108)
pg_aggregate.c (r1.93 -> r1.94)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/pg_aggregate.c?r1=1.93&r2=1.94)
pgsql/src/backend/commands:
functioncmds.c (r1.95 -> r1.96)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/functioncmds.c?r1=1.95&r2=1.96)
pgsql/src/backend/nodes:
copyfuncs.c (r1.394 -> r1.395)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/copyfuncs.c?r1=1.394&r2=1.395)
equalfuncs.c (r1.323 -> r1.324)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/equalfuncs.c?r1=1.323&r2=1.324)
outfuncs.c (r1.326 -> r1.327)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/outfuncs.c?r1=1.326&r2=1.327)
pgsql/src/backend/parser:
gram.y (r2.616 -> r2.617)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y?r1=2.616&r2=2.617)
keywords.c (r1.198 -> r1.199)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/keywords.c?r1=1.198&r2=1.199)
parse_expr.c (r1.228 -> r1.229)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_expr.c?r1=1.228&r2=1.229)
parse_func.c (r1.202 -> r1.203)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_func.c?r1=1.202&r2=1.203)
parse_utilcmd.c (r2.13 -> r2.14)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_utilcmd.c?r1=2.13&r2=2.14)
pgsql/src/backend/utils/adt:
regproc.c (r1.107 -> r1.108)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/regproc.c?r1=1.107&r2=1.108)
ruleutils.c (r1.275 -> r1.276)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/ruleutils.c?r1=1.275&r2=1.276)
pgsql/src/backend/utils/fmgr:
funcapi.c (r1.39 -> r1.40)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/fmgr/funcapi.c?r1=1.39&r2=1.40)
pgsql/src/bin/pg_dump:
pg_dump.c (r1.493 -> r1.494)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_dump.c?r1=1.493&r2=1.494)
pgsql/src/bin/psql:
describe.c (r1.181 -> r1.182)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/describe.c?r1=1.181&r2=1.182)
pgsql/src/include/catalog:
catversion.h (r1.468 -> r1.469)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.468&r2=1.469)
namespace.h (r1.54 -> r1.55)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/namespace.h?r1=1.54&r2=1.55)
pg_proc.h (r1.506 -> r1.507)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h?r1=1.506&r2=1.507)
pgsql/src/include/nodes:
parsenodes.h (r1.366 -> r1.367)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/parsenodes.h?r1=1.366&r2=1.367)
pgsql/src/include/parser:
parse_func.h (r1.59 -> r1.60)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/parser/parse_func.h?r1=1.59&r2=1.60)
pgsql/src/interfaces/ecpg/preproc:
preproc.y (r1.368 -> r1.369)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/preproc.y?r1=1.368&r2=1.369)
pgsql/src/pl/plpgsql/src:
pl_comp.c (r1.126 -> r1.127)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_comp.c?r1=1.126&r2=1.127)
pgsql/src/pl/plpython:
plpython.c (r1.110 -> r1.111)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/plpython.c?r1=1.110&r2=1.111)
pgsql/src/test/regress/expected:
plpgsql.out (r1.64 -> r1.65)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/plpgsql.out?r1=1.64&r2=1.65)
polymorphism.out (r1.12 -> r1.13)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/polymorphism.out?r1=1.12&r2=1.13)
pgsql/src/test/regress/sql:
plpgsql.sql (r1.54 -> r1.55)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/plpgsql.sql?r1=1.54&r2=1.55)
polymorphism.sql (r1.5 -> r1.6)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/polymorphism.sql?r1=1.5&r2=1.6)