Auto merge of #706 - cactorium:master, r=alexcrichton
Auto merge of #706 - cactorium:master, r=alexcrichton

Add IPV6_JOIN_GROUP and IPV6_LEAVE_GROUP to uclibc

Hello! Just some minor fixes so that net2 compiles correctly on uclibc

rust-lang/libc,rust-lang-nursery/libc,rust-lang/libc,cactorium/libc,rust-lang-nursery/libc,rust-lang/libc,cactorium/libc,cactorium/libc,rust-lang-nursery/libc