C++: Improve the example for cpp/return-stack-allocated-memory.

Author: geoffw0

cpp/ql/src/Likely Bugs/Memory Management/ReturnStackAllocatedMemory.cpp

@@ -1,7 +1,5 @@
-Record* fixRecord(Record* r) {
-	Record myRecord = *r;
-	delete r;
+Record *mkRecord(int value) {
+	Record myRecord(value);
 
-	myRecord.fix();
-	return &myRecord; //returns reference to myRecord, which is a stack-allocated object
-}
+	return &myRecord; // BAD: return a pointer to `myRecord`, which is a stack-allocated object
+}