Implement horizontal mouse wheel events support for wxMSW.

Handle WM_MOUSEHWHEEL messages and translate them to the corresponding
wxMouseEvents.

Closes #14105.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70962 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/window.h

@@ -345,7 +345,8 @@ public:
 
     bool HandleMouseEvent(WXUINT msg, int x, int y, WXUINT flags);
     bool HandleMouseMove(int x, int y, WXUINT flags);
-    bool HandleMouseWheel(WXWPARAM wParam, WXLPARAM lParam);
+    bool HandleMouseWheel(wxMouseWheelAxis axis,
+                          WXWPARAM wParam, WXLPARAM lParam);
 
     bool HandleChar(WXWPARAM wParam, WXLPARAM lParam);
     bool HandleKeyDown(WXWPARAM wParam, WXLPARAM lParam);