Set a new attribute to the builder with an arbitrary value.
If an attribute with
attr_type already exists in the builder then it is changed to the new value, otherwise an attribute is
The memory in
value is copied by the builder.
null may be specified for the
value argument, in which case an empty attribute is created. [const
] may be specified for the length, in which case an invalid attribute is created in the PKCS#11 style.
the attribute type
the new attribute memory
the length of the memory