[3315] Small cppcheck issue fixed

src/lib/dhcp/iface_mgr.h

@@ -1026,7 +1026,7 @@ private:
     /// error occurs during opening a socket, or NULL if exception should
     /// be thrown upon error.
     bool openMulticastSocket(Iface& iface,
-                             const isc::asiolink::IOAddress addr,
+                             const isc::asiolink::IOAddress& addr,
                              const uint16_t port,
                              IfaceMgrErrorMsgCallback error_handler = NULL);
 

src/lib/dhcp/iface_mgr_bsd.cc

@@ -152,7 +152,7 @@ IfaceMgr::setMatchingPacketFilter(const bool /* direct_response_desired */) {
 
 bool
 IfaceMgr::openMulticastSocket(Iface& iface,
-                              const isc::asiolink::IOAddress addr,
+                              const isc::asiolink::IOAddress& addr,
                               const uint16_t port,
                               IfaceMgrErrorMsgCallback error_handler) {
     try {

src/lib/dhcp/iface_mgr_linux.cc

@@ -536,7 +536,7 @@ bool IfaceMgr::os_receive4(struct msghdr&, Pkt4Ptr&) {
 
 bool
 IfaceMgr::openMulticastSocket(Iface& iface,
-                              const isc::asiolink::IOAddress addr,
+                              const isc::asiolink::IOAddress& addr,
                               const uint16_t port,
                               IfaceMgrErrorMsgCallback error_handler) {
     // This variable will hold a descriptor of the socket bound to

src/lib/dhcp/iface_mgr_sun.cc

@@ -156,7 +156,7 @@ IfaceMgr::setMatchingPacketFilter(const bool /* direct_response_desired */) {
 
 bool
 IfaceMgr::openMulticastSocket(Iface& iface,
-                              const isc::asiolink::IOAddress addr,
+                              const isc::asiolink::IOAddress& addr,
                               const uint16_t port,
                               IfaceMgrErrorMsgCallback error_handler) {
     try {