Checks if the default of this IRSB a direct jump or not.

def _is_defaultexit_direct_jump(self):
        """
        Checks if the default of this IRSB a direct jump or not.
        """
        if not (self.jumpkind == 'Ijk_InvalICache' or self.jumpkind == 'Ijk_Boring' or self.jumpkind == 'Ijk_Call'):
            return False

        target = self.default_exit_target
        return target is not None