dhcp6: reset and allocate message buffer in build
Merge pull request #255 from mtomaschewski/dhcp6

dhcp6: reset and allocate message buffer in build
client: wait for optional leases, just don't fail

When waiting for a group-optional lease pair (dhcp4 or dhcp6) and
one arrives, wait for the second one until timeout and recheck the
results then (bnc#876848,bnc#879127).
Merge remote-tracking branch 'mt/dhcp4or6' into testing