netatalk: bump to version 3.0.5

Make it use external instead of bundled libevent - it's better for size
reasons (avoiding possible duplication) and security reasons (easier to
upgrade one global library than possibly two or more, and generally
upstream would probably be more responsive to those).

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