Fix Qt include statements

Change
 #include <QtCore/QDebug>
to
 #include <QtCore/qdebug.h>
according to the coding style.

Change-Id: Ie8cf4d28fc0ec7f95fe86806e5402173a0c63cb7
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
Reviewed-by: Andre de la Rocha <andre.rocha@qt.io>