QtXml: make some constructors explicit

This is a semi-automatic search, so I'm
reasonably sure that all the exported ones
have been caught.

Change-Id: Ibb889038a583f419399cd044908d481413b2c48f
Reviewed-by: Richard J. Moore <rich@kde.org>

src/xml/sax/qxml.h

@@ -158,7 +158,7 @@ class Q_XML_EXPORT QXmlInputSource
 {
 public:
     QXmlInputSource();
-    QXmlInputSource(QIODevice *dev);
+    explicit QXmlInputSource(QIODevice *dev);
     virtual ~QXmlInputSource();
 
     virtual void setData(const QString& dat);