wrong namespace for address utilities
Address utilities e.g. firstAddrInPrefix are declared in the isc::dhcp namespace instead of the isc::asiolink one: in fact the namespace was not updated when they were moved to src/lib/asiolink.
Address utilities e.g. firstAddrInPrefix are declared in the isc::dhcp namespace instead of the isc::asiolink one: in fact the namespace was not updated when they were moved to src/lib/asiolink.