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.

src/test/regress/sql/polymorphism.sql

@@ -427,6 +427,13 @@ create aggregate build_group(int8, integer) (
   STYPE = int8[]
 );
 
+-- check that we can apply functions taking ANYARRAY to pg_stats
+select distinct array_ndims(histogram_bounds) from pg_stats
+where histogram_bounds is not null;
+
+-- such functions must protect themselves if varying element type isn't OK
+select max(histogram_bounds) from pg_stats;
+
 -- test variadic polymorphic functions
 
 create function myleast(variadic anyarray) returns anyelement as $$