Linux Ethernet Bridging - Jun 2014 - [PATCH 0/2 net-next] bridge: fix bugs introduced by last multicast patchset

Once my last patchset got applied, I got slapped by an automatic smatch
and build bot. Here are two patches fixing the according issues, a potential
null pointer dereference and a compile error when compiling without IPv6.

[PATCH 1/2] is probably not the ideal solution - the assignment of the
group and max_delay is still a mess and has subtle differences between
IGMPv2, IGMPv3, MLDv1 and MLDv2. That should probably be fixed $later.
But for now, I think the easier fix might be better, restoring the
behaviour before my "adhere to querier mechanism" patch and therefore
keeping things bisect'able.

Cheers, Linus