Auto merge of #714 - dhduvall:master, r=alexcrichton

struct addrinfo needs padding on Solaris/SPARC

64-bit Solaris/SPARC has a 4-byte pad before `ai_addrlen` for historical reasons (`ai_addrlen` used to be defined as a `size_t`, which is 4 bytes in ILP32 and 8 in LP64, but was converted to a 4-byte `socklen_t` in Solaris 10, which necessitated padding for (more or less) binary compatibility).

See rust-lang/rust#43649.