package/sconeserver: needs shared libs

sconeserver wants to use dlopen(), unconditionally: it does not try to
detect it, and it can't work without it (the code is not conditional).

Fixes:
    http://autobuild.buildroot.org/results/e92/e929799366e6f574c7b08d8635b18623afd3e3e1/



[Peter: drop uClibc dependency, adjust commit message]
Reported-by: Matthew Weber <matt@thewebers.ws>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>