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

src/Mod/PartDesign/App/Body.h

@@ -27,7 +27,7 @@
 #include <App/PropertyStandard.h>
 #include <Mod/Part/App/BodyBase.h>
 
-#include <boost/signals2.hpp>
+#include <boost_signals2.hpp>
 
 namespace App {
     class Origin;

src/Mod/PartDesign/App/ShapeBinder.h

@@ -25,7 +25,7 @@
 #define PARTDESIGN_DATUMSHAPE_H
 
 #include <QString>
-#include <boost/signals2.hpp>
+#include <boost_signals2.hpp>
 #include <App/PropertyLinks.h>
 #include <Mod/Part/App/DatumFeature.h>
 

src/Mod/PartDesign/Gui/TaskTransformedMessages.h

@@ -25,7 +25,7 @@
 #define GUI_TASKVIEW_TaskTransformedMessages_H
 
 #include <Gui/TaskView/TaskView.h>
-#include <boost/signals2.hpp>
+#include <boost_signals2.hpp>
 
 class Ui_TaskTransformedMessages;
 typedef boost::signals2::connection Connection;

src/Mod/PartDesign/Gui/WorkflowManager.h

@@ -23,7 +23,7 @@
 #ifndef WORKFLOWMANAGER_H_PB7A5GCM
 #define WORKFLOWMANAGER_H_PB7A5GCM
 
-#include <boost/signals2.hpp>
+#include <boost_signals2.hpp>
 #include <map>
 
 namespace App {