Fix QEventDispatcherBlackberry build when debug is on

Change-Id: Ia00d0f32e7d552421cc230ffca25085ab0a3a31e
Reviewed-by: Andreas Holzammer <andreas.holzammer@kdab.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>

src/corelib/kernel/qeventdispatcher_blackberry.cpp

@@ -50,6 +50,7 @@
 //#define QEVENTDISPATCHERBLACKBERRY_DEBUG
 
 #ifdef QEVENTDISPATCHERBLACKBERRY_DEBUG
+#include <QThread>
 #define qEventDispatcherDebug qDebug() << QThread::currentThread()
 #else
 #define qEventDispatcherDebug QT_NO_QDEBUG_MACRO()