Fix vrouter-agent crash
Fix vrouter-agent crash

Iterator pointing to deleted element was getting incremented.

Change-Id: Ia32fca1e509e83216fe435b49166f8db535ec230
Closes-Bug: #1764641

rombie/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller