move class fwd decl to global namespace
move class fwd decl to global namespace


Former-commit-id: e300e0faf5e5742139b1b4f28bde793ad7c401b9
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin