Setting QT_NO_DEBUG should not remove symbols

Removing symbols when defining QT_NO_DEBUG is a bad idea.
In this case it means that you can't compile corelib as a
release build and widgets as debug without getting an
undefined symbol.

Instead leave the method in the release build, but simply don't
call it.

Change-Id: I50426aefd62e82bccd933323aa0f67c6e5294961
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/kernel/qcoreapplication.cpp

@@ -506,7 +506,6 @@ QThread *QCoreApplicationPrivate::mainThread()
     return theMainThread;
 }
 
-#if !defined (QT_NO_DEBUG) || defined (QT_MAC_FRAMEWORK_BUILD)
 void QCoreApplicationPrivate::checkReceiverThread(QObject *receiver)
 {
     QThread *currentThread = QThread::currentThread();
@@ -523,7 +522,6 @@ void QCoreApplicationPrivate::checkReceiverThread(QObject *receiver)
     Q_UNUSED(currentThread);
     Q_UNUSED(thr);
 }
-#endif
 
 #endif // QT_NO_QOBJECT
 

src/corelib/kernel/qcoreapplication_p.h

@@ -116,9 +116,7 @@ public:
     static QThread *mainThread();
     static void sendPostedEvents(QObject *receiver, int event_type, QThreadData *data);
 
-#if !defined (QT_NO_DEBUG) || defined (QT_MAC_FRAMEWORK_BUILD)
     void checkReceiverThread(QObject *receiver);
-#endif
     void cleanupThreadData();
 #endif // QT_NO_QOBJECT