Replace qVariantValue() with qvariant_cast().

qVariantvalue() is deprecated in Qt 5. qvariant_cast() does
the same thing and works in Qt 4 and Qt 5.

Change-Id: I922329d3a47fe394669f5d97a25f0825d3d2dea5
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/git/gitplugin.cpp

@@ -815,7 +815,7 @@ static inline GitClientMemberFunc memberFunctionFromAction(const QObject *o)
         if (const QAction *action = qobject_cast<const QAction *>(o)) {
             const QVariant v = action->data();
             if (qVariantCanConvert<GitClientMemberFunc>(v))
-                return qVariantValue<GitClientMemberFunc>(v);
+                return qvariant_cast<GitClientMemberFunc>(v);
         }
     }
     return 0;