Fix possible SEGV if the sender object list was null and thread support enabled

Commit manually cherry-picked from 8e653076.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

src/kernel/qobject.cpp

@@ -1101,20 +1101,20 @@ bool TQObject::event( TQEvent *e )
 		    || (d->ownThread == TQThread::currentThreadObject()))
 #endif // TQT_THREAD_SUPPORT
 		{
-		    TQSenderObjectList* sol;
-		    TQObject* oldSender = 0;
-		    sol = senderObjects;
+		    TQObject *oldSender = nullptr;
+		    TQSenderObjectList *sol = senderObjects;
+		    if ( sol )
+		    {
 #ifdef TQT_THREAD_SUPPORT
-		    sol->listMutex->lock();
+			sol->listMutex->lock();
 #endif // TQT_THREAD_SUPPORT
-		    if ( sol ) {
 			oldSender = sol->currentSender;
 			sol->ref();
 			sol->currentSender = metaEvent->sender();
-		    }
 #ifdef TQT_THREAD_SUPPORT
-		    sol->listMutex->unlock();
+			sol->listMutex->unlock();
 #endif // TQT_THREAD_SUPPORT
+		    }
 		    TQUObject *o = metaEvent->data();
 		    if (metaEvent->type() == TQMetaCallEvent::MetaCallEmit) {
 			tqt_emit( metaEvent->id(), o );
@@ -1122,25 +1122,31 @@ bool TQObject::event( TQEvent *e )
 		    if (metaEvent->type() == TQMetaCallEvent::MetaCallInvoke) {
 			tqt_invoke( metaEvent->id(), o );
 		    }
+		    if ( sol )
+		    {
 #ifdef TQT_THREAD_SUPPORT
-		    sol->listMutex->lock();
+			sol->listMutex->lock();
 #endif // TQT_THREAD_SUPPORT
-		    if (sol ) {
 			sol->currentSender = oldSender;
-			if ( sol->deref() ) {
+			if ( sol->deref() )
+			{
 #ifdef TQT_THREAD_SUPPORT
 			    sol->listMutex->unlock();
 #endif // TQT_THREAD_SUPPORT
 			    delete sol;
-			    sol = NULL;
+			    sol = nullptr;
 			}
 		    }
 #ifdef TQT_THREAD_SUPPORT
-		    if (sol) sol->listMutex->unlock();
+		    if (sol)
+		    {
+			sol->listMutex->unlock();
+		    }
 #endif // TQT_THREAD_SUPPORT
 		}
 #ifdef TQT_THREAD_SUPPORT
-		else {
+		else
+		{
 		    tqWarning("TQObject: Ignoring metacall event from non-owning thread");
 		}
 #endif // TQT_THREAD_SUPPORT