pgsql: The original implementation of polymorphic aggregates didn't

Log Message:
-----------
The original implementation of polymorphic aggregates didn't really get the
checking of argument compatibility right; although the problem is only exposed
with multiple-input aggregates in which some arguments are polymorphic and
some are not. Per bug #3852 from Sokolov Yura.

Modified Files:
--------------
pgsql/src/backend/catalog:
pg_aggregate.c (r1.89 -> r1.90)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/pg_aggregate.c?r1=1.89&r2=1.90)
pgsql/src/backend/executor:
nodeAgg.c (r1.155 -> r1.156)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/executor/nodeAgg.c?r1=1.155&r2=1.156)
pgsql/src/backend/optimizer/util:
clauses.c (r1.253 -> r1.254)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/clauses.c?r1=1.253&r2=1.254)
pgsql/src/backend/parser:
parse_coerce.c (r2.160 -> r2.161)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_coerce.c?r1=2.160&r2=2.161)
parse_func.c (r1.200 -> r1.201)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_func.c?r1=1.200&r2=1.201)
parse_oper.c (r1.100 -> r1.101)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_oper.c?r1=1.100&r2=1.101)
pgsql/src/include/parser:
parse_coerce.h (r1.74 -> r1.75)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/parser/parse_coerce.h?r1=1.74&r2=1.75)
pgsql/src/test/regress/expected:
polymorphism.out (r1.11 -> r1.12)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/polymorphism.out?r1=1.11&r2=1.12)
pgsql/src/test/regress/sql:
polymorphism.sql (r1.4 -> r1.5)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/polymorphism.sql?r1=1.4&r2=1.5)