Add test case.

Author: zlaski-semmle

cpp/ql/test/library-tests/builtins/builtins/builtins.expected

@@ -1,4 +1,6 @@
 | choose_expr.c:3:13:3:42 | __builtin_choose_expr |
+| types.c:4:9:4:57 | __builtin_types_compatible_p |
+| types.c:6:16:6:65 | __builtin_types_compatible_p |
 | varargs.c:7:5:7:32 | __builtin_va_start |
 | varargs.c:9:13:9:37 | __builtin_va_arg |
 | varargs.c:11:5:11:24 | __builtin_va_end |

cpp/ql/test/library-tests/builtins/builtins/types.c

@@ -0,0 +1,11 @@
+
+int main(int argc, char **argv) {
+    char *s;
+    if (__builtin_types_compatible_p(__typeof__(s), long)) {
+        puts("long");
+    } else if (__builtin_types_compatible_p(__typeof__(s), char*)) {
+        puts("str");
+    }
+    return (0);
+};
+