sconeserver: fix depends

sconeserver selects packages that have other depends that aren't taken
account of.
Fixes
http://autobuild.buildroot.net/results/6e858387cfcb3f8d7422a29855a6a3c770d70c0e


among probably others.

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