Handle non-qmake projects without kits

Make it possible to add kits again after all kits were removed
from a non qmake project.

Task-number: QTCREATORBUG-7814
Change-Id: I38967cd4c106b95288b7020fe325d8cfe2688a7c
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

src/plugins/qt4projectmanager/qt4project.cpp

@@ -1367,6 +1367,11 @@ void Qt4Project::configureAsExampleProject(const QStringList &platforms)
     ProjectExplorer::ProjectExplorerPlugin::instance()->requestProjectModeUpdate(this);
 }
 
+bool Qt4Project::supportsNoTargetPanel() const
+{
+    return true;
+}
+
 // All the Qt4 run configurations should share code.
 // This is a rather suboptimal way to do that for disabledReason()
 // but more pratical then duplicated the code everywhere