package: add spawn-fcgi package

Closes #417,

New package spawn-fcgi, basically a FastCGI process spawner.
This was previously included in lighttpd up to version 1.4.22 and is now
a separate project.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>