C++: Silence a number of bogus consistency errors in syntax zoo

These were due to several functions occurring that would have the same TRAP
key. By making the functions static the TRAP keys will differ from each other.

cpp/ql/test/library-tests/syntax-zoo/constructorinitializer.cpp

@@ -3,7 +3,7 @@ class C {
 		C(int x, int y);
 };
 
-void f() {
+static void f() {
 	int i, j, k, l;
 	C c(i + j, k - l);
 }