Return strings.

def c_source(self):
        """Return strings."""
        relocs = Relocs(
            ''.join(self.c_self_relocs()), *self.c_module_relocs()
        )
        return Source(
            ''.join(self.c_typedefs()),
            '' if self.opts.no_structs else self.c_struct(),
            ''.join(self.c_hashes()),
            ''.join(self.c_var_decls()),
            relocs,
            self.c_loadlib() + ''.join(self.c_getprocs())
        )