C++: Fix database inconsistency issue from ODR violation.

cpp/ql/test/library-tests/ir/range-analysis/SimpleRangeAnalysis_tests.cpp

@@ -1,4 +1,4 @@
-template<typename T> void range(T);
+#include "test_util.h"
 
 struct List {
   struct List* next;

cpp/ql/test/library-tests/ir/range-analysis/test.cpp

@@ -1,4 +1,4 @@
-template<typename T> void range(T value);
+#include "test_util.h"
   int f1(int x, int y) {
     if (x < 500) {
       if (x > 400) {

cpp/ql/test/library-tests/ir/range-analysis/test_util.h

@@ -0,0 +1 @@
+template<typename T> void range(T value);