stun: memset saddr before binding

We need to zero out data before we actually do the bind, otherwise
uninitialized crap can be in saddr.

Found by coverty scanner.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
keypair: add missing include file

Include curve.h so that it also finds the selftest.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>