udhcpc[6]: initialize entire sockaddr_ll

I see random field values like sll_hatype=0x267 when I strace.
They seem to not matter, but just in case they sometimes do,
let's at least have deterministic values (via memset(0)).

function                                             old     new   delta
change_listen_mode                                   308     322     +14

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
4 files changed