As usual, gcc finds some real problems but also reports a ton of noise. Fix the problems and quiet the noise.

In some situations, gethostbyname can return an empty address list. R=rsc http://codereview.appspot.com/6443097

Not all systems have ss_len, and we've never set it before. R=rsc http://codereview.appspot.com/6497102

R=rsc http://codereview.appspot.com/6495109

Fix build error and warning on OpenBSD 5.1, as reported by Dimitri Sokolyuk. R=rsc http://codereview.appspot.com/6350044

The function p9dialparse() returns the host as a sockaddr_storage structure instead of a u32int, to be able to handle both IPv4 and IPv6 addresses. Because the sockaddr_storage structure also handle port numbers and Unix path names, there is no longer need to set them in the calling functions. However, these values are still returned for convenience. The sockaddr_in and sockaddr_un structures have been replaced by sockaddr_storage to handle Unix, IPv4 and IPv6 sockets. Names and addresses are resolved using either gethostbyname() or getaddrinfo() functions. The getaddrinfo() function is documented in RFC2553 and standardized since POSIX.1-2001. It supports both IPv4 and IPv6 addresses. The gethostbyname() function is deprecated since POSIX.1-2008. However, some libc implementations don't handle getaddrinfo() properly, thus we preferred to try gethostbyname() first. I've tried to preserve most of the old code logic to prevent from surprising or unwanted behavior. R=rsc http://codereview.appspot.com/6255068

R=rsc http://codereview.appspot.com/396042