update spawn-fcgi to 1.6.4

Signed-off-by: Ricky Elrod <ricky@elrod.me>
libtorrent: update to 0.13.4
rtorrent: update to 0.9.4
Merge pull request #2956 from Fuuzetsu/rtorrent

rtorrent
Merge pull request #2934 from CodeBlock/spawn-fcgi-update

update spawn-fcgi to 1.6.4