Replace std::ignore with boost::ignore_unused()

According to https://isocpp.org/blog/2016/09/quick-q-stdignore-for-ignoring-unused-variable std::ignore is not supposed to be used for this

src/App/FeatureTest.cpp

@@ -22,6 +22,9 @@
 
 
 #include "PreCompiled.h"
+#ifndef _PreComp_
+#include <boost/core/ignore_unused.hpp>
+#endif
 
 #include <Base/Exception.h>
 #include <Base/Unit.h>
@@ -140,10 +143,10 @@ DocumentObjectExecReturn *FeatureTest::execute()
 
     Enumeration enumObj4("Single item");
     enumObj4.setEnums(enums);
-    std::ignore = enumObj4 == enumObj2;
+    boost::ignore_unused(enumObj4 == enumObj2);
     enumObj4.setEnums(nullptr);
     enumObj4 = enumObj2;
-    std::ignore = enumObj4 == enumObj4.getCStr();
+    boost::ignore_unused(enumObj4 == enumObj4.getCStr());
 
     Enumeration enumObj5(enums, enums[3]);
     enumObj5.isValue(enums[2]);

src/App/Metadata.cpp

@@ -25,6 +25,7 @@
 #ifndef _PreComp_
 # include <memory>
 # include <sstream>
+# include <boost/core/ignore_unused.hpp>
 #endif
 
 #include "Metadata.h"
@@ -61,7 +62,7 @@ namespace MetadataInternal {
         void warning(const SAXParseException& toCatch)
         {
             // Don't deal with warnings at all
-            std::ignore = toCatch;
+            boost::ignore_unused(toCatch);
         }
 
         void error(const SAXParseException& toCatch)

src/App/PreCompiled.h

@@ -88,6 +88,7 @@
 // Boost
 #include <boost_signals2.hpp>
 #include <boost/bind/bind.hpp>
+#include <boost/core/ignore_unused.hpp>
 #include <boost/regex.hpp>
 
 #include <boost/utility.hpp>

src/Gui/PreCompiled.h

@@ -84,6 +84,7 @@
 #include <boost_signals2.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/bind/bind.hpp>
+#include <boost/core/ignore_unused.hpp>
 #include <boost/filesystem/exception.hpp>
 #include <boost/filesystem/path.hpp>
 #include <boost/filesystem/operations.hpp>

src/Gui/SoFCColorBar.cpp

@@ -23,6 +23,7 @@
 #include "PreCompiled.h"
 
 #ifndef _PreComp_
+# include <boost/core/ignore_unused.hpp>
 # include <Inventor/actions/SoGetBoundingBoxAction.h>
 # include <Inventor/actions/SoGLRenderAction.h>
 # include <Inventor/events/SoMouseButtonEvent.h>
@@ -221,7 +222,7 @@ SoFCColorBarBase* SoFCColorBar::getActiveBar() const
 
 void SoFCColorBar::setViewportSize( const SbVec2s& size )
 {
-    std::ignore = size;
+    boost::ignore_unused(size);
 }
 
 void SoFCColorBar::setRange( float fMin, float fMax, int prec )

src/Mod/Part/App/TopoShape.cpp

@@ -162,6 +162,7 @@
 #endif // _PreComp_
 
 #include <boost/algorithm/string/predicate.hpp>
+#include <boost/core/ignore_unused.hpp>
 
 #include <App/Material.h>
 #include <Base/BoundBox.h>
@@ -4280,7 +4281,7 @@ TopoShape &TopoShape::makeTransform(const TopoShape &shape, const gp_Trsf &trsf,
 
 TopoShape &TopoShape::makeGTransform(const TopoShape &shape, const Base::Matrix4D &rclTrf, const char *op, bool copy)
 {
-    std::ignore = op;
+    boost::ignore_unused(op);
     _Shape = shape.transformGShape(rclTrf, copy);
     return *this;
 }

src/Mod/PartDesign/Gui/PreCompiled.h

@@ -42,6 +42,7 @@
 
 // Boost
 #include <boost/bind/bind.hpp>
+#include <boost/core/ignore_unused.hpp>
 
 // OCC
 #include <Standard_math.hxx>

src/Mod/PartDesign/Gui/TaskShapeBinder.cpp

@@ -24,6 +24,7 @@
 #include "PreCompiled.h"
 
 #ifndef _PreComp_
+# include <boost/core/ignore_unused.hpp>
 # include <QAction>
 # include <QMessageBox>
 #endif
@@ -61,7 +62,7 @@ TaskShapeBinder::TaskShapeBinder(ViewProviderShapeBinder* view, bool newObj, QWi
     , ui(new Ui_TaskShapeBinder)
     , vp(view)
 {
-    std::ignore = newObj;
+    boost::ignore_unused(newObj);
 
     // we need a separate container widget to add all controls to
     proxy = new QWidget(this);