Fix some gcc build warnings

Author: nyalldawson

src/core/layertree/qgslayertreenode.cpp

@@ -30,7 +30,8 @@ QgsLayerTreeNode::QgsLayerTreeNode( QgsLayerTreeNode::NodeType t, bool checked )
 }
 
 QgsLayerTreeNode::QgsLayerTreeNode( const QgsLayerTreeNode &other )
-  : mNodeType( other.mNodeType )
+  : QObject( nullptr )
+  , mNodeType( other.mNodeType )
   , mChecked( other.mChecked )
   , mExpanded( other.mExpanded )
   , mProperties( other.mProperties )

src/plugins/georeferencer/qgsgcplist.cpp

@@ -19,6 +19,7 @@
 #include "qgsgcplist.h"
 
 QgsGCPList::QgsGCPList( const QgsGCPList &list )
+  :  QList<QgsGeorefDataPoint *>()
 {
   clear();
   QgsGCPList::const_iterator it = list.constBegin();

src/plugins/georeferencer/qgsgeorefdatapoint.cpp

@@ -39,8 +39,8 @@ QgsGeorefDataPoint::QgsGeorefDataPoint( QgsMapCanvas *srcCanvas, QgsMapCanvas *d
 }
 
 QgsGeorefDataPoint::QgsGeorefDataPoint( const QgsGeorefDataPoint &p )
+  : QObject( nullptr )
 {
-  Q_UNUSED( p );
   // we share item representation on canvas between all points
 //  mGCPSourceItem = new QgsGCPCanvasItem(p.srcCanvas(), p.pixelCoords(), p.mapCoords(), p.isEnabled());
 //  mGCPDestinationItem = new QgsGCPCanvasItem(p.dstCanvas(), p.pixelCoords(), p.mapCoords(), p.isEnabled());