nref: put refcount at the end of the test struct

test/CMakeLists.txt

@@ -19,6 +19,7 @@ add_executable(neo_test neo_test.cpp)
 include(string/string.cmake)
 
 target_sources(neo_test PRIVATE
+    list.cpp
     nref.cpp
 )
 

test/nref.cpp

@@ -15,8 +15,9 @@
  * code rather than the fun quirks C++ is infamous for.
  */
 extern "C" struct nref_test {
-	NREF_FIELD;
 	bool *called;
+	/* NREF_FIELD is not at the beginning to ensure offsets are subtracted */
+	NREF_FIELD;
 };
 
 void test_destroy(struct nref_test *ptr)