Fix missing member in QXmlStreamReaderPrivate::init

Add missing lastAttributeIsCData

Change-Id: I66429d35da0451eefe8d14e031306b16df910d0f
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/corelib/serialization/qxmlstream.cpp

@@ -822,6 +822,7 @@ QXmlStreamReaderPrivate::QXmlStreamReaderPrivate(QXmlStreamReader *q)
 void QXmlStreamReaderPrivate::init()
 {
     scanDtd = false;
+    lastAttributeIsCData = false;
     token = -1;
     token_char = 0;
     isEmptyElement = false;