Build fails on Solaris without 'sys/socket.h' included

[l1gi]

Hi,

I was trying to uprev rtorrent on Solaris and found that it doesn build without AF_UNSPEC, AF_INET, AF_INET6 defined.

Attached patch resolves that. Consider adopting it, please.

Thank you

Martin socket.txt

[rakshasa]

Please provide a build process for building an image of solaris on e.g. virtualbox with everything required to build rtorrent.