lighttpd: bump version

lighttpd: bump version

Closes #419.

lighttpd 1.4.23 is out, there are many bugfixes from 1.4.20 currently in
buildroot:
 *  Fix workaround for incorrect path info/scriptname if fastcgi prefix is
    ”/” (fixes #729)
 * Finally removed spawn-fcgi
 * Fix bug with FastCGI request id overflow under high load; just use always
   id 1 as we don’t use multiplexing. (thx jgray)
 * Workaround broken operating systems: check for trailing ’/’ in filenames
   (fixes #1989)
Plus fixes from 1.4.22 and 1.4.21.

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