Addrinfo.getaddrinfo and .foreach now accepts :timeout in seconds as
a keyword argument. If getaddrinfo_a(3) is available, the timeout will be
applied for name resolution. Otherwise, it will be ignored.

Socket.tcp accepts :resolv_timeout to use this feature.

This commit is retry of 6382f5cc.
Test was failed on Solaris machines which don't have "http" in
/etc/services. In this commit, use "ssh" instead.