SERVER-10159 Don't 'done' the BSONObjBuilder right before we call its destructor
SERVER-1105 Do not test role->privilege mappings in authorization_manager_test.

Also, beef up privilege_document_parser_test, instead of testing role parsing in
authorization_manager_test.

The role->privilege mapping belongs to the RoleGraph, and the authorization of actions
to the AuthorizationSession.  Actual parsing belongs in privilege_document_parser_test.