QmlJS: Compile fix

Amends bd05384765.

Change-Id: I45475798cdc1d4de997e694596f0c18009241492
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/libs/qmljs/qmljsscanner.cpp

@@ -25,6 +25,8 @@
 
 #include <qmljs/qmljsscanner.h>
 
+#include <QDebug>
+
 #include <algorithm>
 
 using namespace QmlJS;