Project: Do not save unconfigured projects

This avoids having .user files when pressing cancel on the Project Mode's
TargetSetupPage.

Change-Id: I09fc8e78c929d6f09a50ee57ef4f59555491c649
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/projectexplorer/project.cpp

@@ -301,6 +301,7 @@ void Project::saveSettings()
     emit aboutToSaveSettings();
     if (!d->m_accessor)
         d->m_accessor = new Internal::UserFileAccessor(this);
+    if (!targets().isEmpty())
         d->m_accessor->saveSettings(toMap(), Core::ICore::mainWindow());
 }