Attached is a trivial patch to allow inet_add_protocol on kernels without CONFIG_NAMESPACES to load non-namespace aware (out of kernel) modules.
For IPv6, there is no such check. Some discussion of that can be found in the archive: http://www.spinics.net/lists/netdev/msg225184.html

I'm ambivalent on whether the check should be there (like in ipv4) or not (like in ipv6). But if it is there, it should use the proper #ifdef.

Paul