dhcp: refuse to configure DHCP IAID if the interface is under renaming

systemd-networkd itself does not start dhcp client, but the code
may be used in other projects. So, check that the interface is under
renaming or not.

src/libsystemd-network/dhcp-identifier.c

@@ -12,6 +12,7 @@
 #include "siphash24.h"
 #include "sparse-endian.h"
 #include "stdio-util.h"
+#include "udev-util.h"
 #include "virt.h"
 
 #define SYSTEMD_PEN    43793
@@ -182,6 +183,13 @@ int dhcp_identifier_set_iaid(
                                 /* not yet ready */
                                 return -EBUSY;
 
+                        r = device_is_renaming(device);
+                        if (r < 0)
+                                return r;
+                        if (r > 0)
+                                /* device is under renaming */
+                                return -EBUSY;
+
                         name = net_get_name(device);
                 }
         }