Add explicit and make public headers compile with -Wzero-as-null-pointer-constant

... or equivalent.

QtBase 5.6 headers already compile that way, so let the other
modules follow suit.

Added explicit where it was missing. This is not a source-
incompatible change, because code that breaks by this is
a bug. Let's not have this sitting around in an LTS.

Change-Id: I579e8714f94884dc555b673c9f85508f17cdc99d
Task-number: QTBUG-45291
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@theqtcompany.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/datavisualization/input/qabstract3dinputhandler.h b/src/datavisualization/input/qabstract3dinputhandler.h
index 64623e67..317cba1f 100644
--- a/src/datavisualization/input/qabstract3dinputhandler.h
+++ b/src/datavisualization/input/qabstract3dinputhandler.h
@@ -50,7 +50,7 @@ public:
     };
 
 protected:
-    explicit QAbstract3DInputHandler(QObject *parent = 0);
+    explicit QAbstract3DInputHandler(QObject *parent = Q_NULLPTR);
 public:
     virtual ~QAbstract3DInputHandler();