[multipathd] dead maps garbage collector fix
[multipathd] dead maps garbage collector fix

The collector could fail to catch all dead maps and/or point mem outside the
maps vector : fix the iteration logic.

unakatsuo/multipath-tools,vijaychauhan/multipath-tools,grzn/multipath-tools-explained,gebi/multipath-tools,unakatsuo/multipath-tools,unakatsuo/multipath-tools,vijaychauhan/multipath-tools,grzn/multipath-tools-explained