Regression: Qt 5 tools no longer built due to static plugin breakage

Change 819d0203e6fd9d27dc4c22e8c3cb8b437998f62a (Use qualified name for QT_MOC_EXPORT_PLUGIN()) breaks compilation of Qt Designer:

.moc/debug-shared/moc_signalsloteditor_plugin.cpp:199: error: 'qt_plugin_instance_qdesigner_internal' has not been declared
.moc/debug-shared/moc_signalsloteditor_plugin.cpp:199: error: 'qt_plugin_query_metadata_qdesigner_internal' has not been declared
.moc/debug-shared/moc_signalsloteditor_plugin.cpp: In function 'const char* SignalSlotEditorPlugin()':
.moc/debug-shared/moc_signalsloteditor_plugin.cpp:199: error: new declaration 'const char* SignalSlotEditorPlugin()'
.moc/debug-shared/moc_signalsloteditor_plugin.cpp:199: error: ambiguates old declaration 'QObject* SignalSlotEditorPlugin()'
.moc/debug-shared/moc_signalsloteditor_plugin.cpp: At global scope:
.moc/debug-shared/moc_signalsloteditor_plugin.cpp:199: error: 'qt_static_plugin_qdesigner_internal' has not been declared
.moc/debug-shared/moc_signalsloteditor_plugin.cpp: In function 'const QStaticPlugin SignalSlotEditorPlugin()':
.moc/debug-shared/moc_signalsloteditor_plugin.cpp:199: error: new declaration 'const QStaticPlugin SignalSlotEditorPlugin()'
.moc/debug-shared/moc_signalsloteditor_plugin.cpp:199: error: ambiguates old declaration 'QObject* SignalSlotEditorPlugin()'
.moc/debug-shared/moc_signalsloteditor_plugin.cpp:199: error: 'qt_plugin_instance_qdesigner_internal' has not been declared

which blocks https://codereview.qt-project.org/#change,33862 and release package building.

The expanded macro looks like:

using namespace qdesigner_internal;
static ::QObject *qt_plugin_instance_qdesigner_internal::SignalSlotEditorPlugin()
{
static ::QPointer< ::QObject> _instance;
if (!_instance)
_instance = new qdesigner_internal::SignalSlotEditorPlugin; return _instance;
}

static const char *qt_plugin_query_metadata_qdesigner_internal::SignalSlotEditorPlugin()
{
return (const char *)qt_pluginMetaData;
}

const ::QStaticPlugin qt_static_plugin_qdesigner_internal::SignalSlotEditorPlugin()
{
::QStaticPlugin plugin =

{ qt_plugin_instance_qdesigner_internal::SignalSlotEditorPlugin, qt_plugin_query_metadata_qdesigner_internal::SignalSlotEditorPlugin}

;
return plugin;
}