vrrp: Proper restore of VMAC interface properties on SIGHUP

On SIGHUP the VMAC flag and base ifindex for a VMAC interface was lost.

Signed-off-by: Jonas Johansson <jonasj76@gmail.com>
Merge pull request #84 from jonasj76/vmac-sighup

Proper restore of VMAC interface properties on SIGHUP