pgsql: Restore enforce_generic_type_consistency's pre-8.3 behavior of

Log Message:
-----------
Restore enforce_generic_type_consistency's pre-8.3 behavior of allowing an
actual argument type of ANYARRAY to match an argument declared ANYARRAY,
so long as ANYELEMENT etc aren't used.  I had overlooked the fact that this
is a possible case while fixing bug #3852; but it is possible because
pg_statistic contains columns declared ANYARRAY.  Per gripe from Corey Horton.

Modified Files:
--------------
    pgsql/src/backend/parser:
        parse_coerce.c (r2.171 -> r2.172)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_coerce.c?r1=2.171&r2=2.172)
    pgsql/src/test/regress/expected:
        polymorphism.out (r1.15 -> r1.16)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/polymorphism.out?r1=1.15&r2=1.16)
    pgsql/src/test/regress/sql:
        polymorphism.sql (r1.8 -> r1.9)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/polymorphism.sql?r1=1.8&r2=1.9)