[2702] Fix for DHCPv4 client renewals (without client-id)

ChangeLog

+5XX.	[func]		marcin,tomek
+	b10-dhcp4: Address renewal now works properly for DHCPv4 clients
+	that do not send client-ids.
+	(Trac #2702, git TBD)
+
 568.	[func]          muks
 	Various message IDs have been renamed to remove the word 'ERROR'
 	from them when they are not logged at ERROR severity level.

src/lib/dhcpsrv/alloc_engine.cc

@@ -274,7 +274,7 @@ AllocEngine::allocateAddress4(const SubnetPtr& subnet,
     }
 
     // Check if there's existing lease for that subnet/clientid/hwaddr combination.
-    Lease4Ptr existing = LeaseMgrFactory::instance().getLease4(hwaddr->hwaddr_, subnet->getID());
+    Lease4Ptr existing = LeaseMgrFactory::instance().getLease4(*hwaddr, subnet->getID());
     if (existing) {
         // We have a lease already. This is a returning client, probably after
         // its reboot.