Clang: Improve anonymous cursors support

With the recent libclang fix the anonymous cursors
are reported properly. So we can use that information
instead of some of our workarounds.

Change-Id: I94401f33e671e6dd08ac7d850c8d5c3dbdd062cc
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

tests/unit/unittest/data/cursor.cpp

@@ -135,3 +135,13 @@ extern int ExternVarStorageClass;
 static void StaticMethodStorageClass() {}
 
 template<class T> const T &InvalidStorageClass(const T &type) { return type; }
+
+namespace Outer {
+namespace {
+
+}
+
+enum {
+    X, Y
+};
+}