C++: Add tests (and fix a missing quote in the alert message).

cpp/ql/src/Critical/GlobalUseBeforeInit.ql

@@ -111,5 +111,5 @@ where
   uninitialisedBefore(v, f) and
   useFunc(v, f)
 select f,
-  "The variable '" + v.getName() +
+  "The variable '" + v.getName() + "'" +
     " is used in this function but may not be initialized when it is called."

cpp/ql/test/query-tests/Critical/GlobalUseBeforeInit/GlobalUseBeforeInit.expected

@@ -0,0 +1 @@
+| test.cpp:27:5:27:6 | f1 | The variable 'b' is used in this function but may not be initialized when it is called. |

cpp/ql/test/query-tests/Critical/GlobalUseBeforeInit/GlobalUseBeforeInit.qlref

@@ -0,0 +1 @@
+Critical/GlobalUseBeforeInit.ql

cpp/ql/test/query-tests/Critical/GlobalUseBeforeInit/test.cpp

@@ -0,0 +1,38 @@
+typedef __builtin_va_list va_list;
+typedef struct {} FILE;
+
+extern FILE * stdin;
+extern FILE * stdout;
+extern FILE * stderr;
+
+#define va_start(args, fmt) __builtin_va_start(args,fmt)
+#define va_end(args) __builtin_va_end(args);
+
+int vfprintf (FILE *, const char *, va_list);
+
+int a = 1;
+int b;
+
+int my_printf(const char * fmt, ...)
+{
+    va_list vl;
+    int ret;
+    va_start(vl, fmt);
+    ret = vfprintf(stdout, fmt, vl);
+    ret = vfprintf(stderr, fmt, vl);
+    va_end(vl);
+    return ret;
+}
+
+int f1()
+{
+    my_printf("%d\n", a + 2);
+    my_printf("%d\n", b + 2); // BAD
+    return 0;
+}
+
+int main()
+{
+    int b = f1();
+    return 0;
+}