Add a check for correct implementation of LWIP_CONST_CAST() to lwip_init()

src/core/init.c

@@ -339,6 +339,11 @@ PACK_STRUCT_END
 void
 lwip_init(void)
 {
+#ifndef LWIP_SKIP_CONST_CHECK
+  int a;
+  LWIP_UNUSED_ARG(a);
+  LWIP_ASSERT("LWIP_CONST_CAST not implemented correctly. Check your lwIP port.", LWIP_CONST_CAST(void*, &a) == &a);
+#endif
 #ifndef LWIP_SKIP_PACKING_CHECK
   LWIP_ASSERT("Struct packing not implemented correctly. Check your lwIP port.", sizeof(struct packed_struct_test) == PACKED_STRUCT_TEST_EXPECTED_SIZE);
 #endif