Gui: fix possible build failure

src/Gui/ArcEngine.cpp

@@ -23,6 +23,7 @@
 #include "PreCompiled.h"
 
 #include "ArcEngine.h"
+#include <limits>
 #include <vector>
 
 # include <Inventor/engines/SoCalculator.h>
@@ -132,4 +133,4 @@ void ArcEngine::defaultValues()
   SO_ENGINE_OUTPUT(pointCount, SoSFInt32, setValue(2));
   SbVec3f point3(7.07f, 7.07f, 0.0);
   SO_ENGINE_OUTPUT(midpoint, SoSFVec3f, setValue(point3));
-}
+}