Zero unused data fields in XClientMessageEvent struct

valgrind was complaining about access to uninitialized data because
unused elements in client_message.data.l array weren't set o any value.

Signed-off-by: Alexander Golubev <fatzer2@gmail.com>
(cherry picked from commit 8a13d9aef4)

src/kernel/qapplication_x11.cpp

@@ -5806,7 +5806,7 @@ void qt_insert_sip( TQWidget* scrolled_widget, int dx, int dy )
     TQScrollInProgress* sip = new TQScrollInProgress( scrolled_widget, dx, dy );
     sip_list->append( sip );
 
-    XClientMessageEvent client_message;
+    XClientMessageEvent client_message = {};
     client_message.type = ClientMessage;
     client_message.window = scrolled_widget->winId();
     client_message.format = 32;