In order to support dynamically linked nodes based on Graphene, add
support for building dynamic libraries for the core Graphene
modules: chain, db, protocol, net, and utilities.
The ID types, object_id and object_id_type, were defined in the db
library, and the protocol library depends on db to get these types.
Technically, the ID types are defined by the protocol and used by the
database, and not vice versa. Therefore these types should be in the
protocol library, and db should depend on protocol to get them.
This commit makes it so.
