* sql/metaclass.lisp: Work-around openmcl's CHANGE-CLASS
changing the type-specifier. Use a lisp type of (OR NULL FOO)
for a specified-type of FOO unless :db-constraints :not-null.
* sql/metaclass.lisp: Work-around openmcl's CHANGE-CLASS
changing the type-specifier. Use a lisp type of (OR NULL FOO)
for a specified-type of FOO unless :db-constraints :not-null.