CppTools: Do not append '/' to fallback header paths

...since this will confuse the completer.

Task-number: QTCREATORBUG-13567
Change-Id: I4172d433f23f3907690d4c00f92fadb68fa354e8
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/cpptools/cppmodelmanager_test.cpp

@@ -75,7 +75,7 @@ public:
     { return directory(_("frameworks"), cleaned); }
 
     QString fileFromSourcesDir(const QString &fileName) const
-    { return directory(_("sources")) + fileName; }
+    { return directory(_("sources")) + QLatin1Char('/') + fileName; }
 };
 
 // TODO: When possible, use this helper class in all tests