Fix build warnings from deprecated Boost headers (they are used internally by Boost). Thanks @wwmayer for the hint.

src/Mod/TechDraw/App/DrawPage.h

@@ -24,7 +24,7 @@
 #ifndef _DrawPage_h_
 #define _DrawPage_h_
 
-#include <boost/signals2.hpp>
+#include <boost_signals2.hpp>
 
 #include <App/DocumentObject.h>
 #include <App/DocumentObjectGroup.h>

src/Mod/TechDraw/App/DrawView.h

@@ -23,7 +23,7 @@
 #ifndef _DrawView_h_
 #define _DrawView_h_
 
-#include <boost/signals2.hpp>
+#include <boost_signals2.hpp>
 
 #include <QCoreApplication>
 #include <QRectF>

src/Mod/TechDraw/Gui/MDIViewPage.cpp

@@ -39,7 +39,7 @@
     #include <QPrinter>
     #include <QPrintDialog>
     #include <QPrintPreviewDialog>
-    #include <boost/signals2.hpp>
+    #include <boost_signals2.hpp>
     #include <boost_bind_bind.hpp>
 
 #endif  // #ifndef _PreComp_

src/Mod/TechDraw/Gui/ViewProviderDrawingView.cpp

@@ -25,7 +25,7 @@
 #include "PreCompiled.h"
 
 #ifndef _PreComp_
-#include <boost/signals2.hpp>
+#include <boost_signals2.hpp>
 #include <boost/signals2/connection.hpp>
 #include <boost_bind_bind.hpp>
 

src/Mod/TechDraw/Gui/ViewProviderDrawingView.h

@@ -25,7 +25,7 @@
 #ifndef TECHDRAWGUI_VIEWPROVIDERVIEW_H
 #define TECHDRAWGUI_VIEWPROVIDERVIEW_H
 
-#include <boost/signals2.hpp> 
+#include <boost_signals2.hpp> 
 
 #include <Gui/ViewProviderFeature.h>
 #include <Gui/ViewProviderDocumentObjectGroup.h>

src/Mod/TechDraw/Gui/ViewProviderPage.cpp

@@ -32,7 +32,7 @@
 # include <QTimer>
 # include <QList>
 # include <QPointer>
-# include <boost/signals2.hpp>
+# include <boost_signals2.hpp>
 # include <boost/signals2/connection.hpp>
 # include <boost_bind_bind.hpp>
 

src/Mod/TechDraw/Gui/ViewProviderPage.h

@@ -28,7 +28,7 @@
 #include <QPointer>
 #include <Gui/ViewProviderDocumentObject.h>
 
-#include <boost/signals2.hpp> 
+#include <boost_signals2.hpp> 
 
 namespace TechDraw{
     class DrawPage;