PyCXX: change typedef of PyCxx_ssize_t to fix compiler warnings with MSVC

src/Gui/SplitView3DInventor.cpp

@@ -728,7 +728,7 @@ Py::Object AbstractSplitViewPy::sequence_item(Py_ssize_t viewIndex)
     return Py::asObject(viewer);
 }
 
-int AbstractSplitViewPy::sequence_length()
+PyCxx_ssize_t AbstractSplitViewPy::sequence_length()
 {
     AbstractSplitView* view = getSplitViewPtr();
     return view->getSize();

src/Gui/SplitView3DInventor.h

@@ -100,7 +100,7 @@ public:
     Py::Object getViewer(const Py::Tuple&);
     Py::Object sequence_item(Py_ssize_t);
     Py::Object close(const Py::Tuple&);
-    int sequence_length();
+    PyCxx_ssize_t sequence_length();
 
 private:
     Gui::MDIViewPy base;