Respect item max sizes in wxBoxSizer.

Don't give more space than the max size, if set, to wxBoxSizer elements.

Closes #11497.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72345 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/sizer.h

@@ -311,6 +311,10 @@ public:
         { return m_minSize; }
     wxSize GetMinSizeWithBorder() const;
 
+    wxSize GetMaxSize() const
+        { return IsWindow() ? m_window->GetMaxSize() : wxDefaultSize; }
+    wxSize GetMaxSizeWithBorder() const;
+
     void SetMinSize(const wxSize& size)
     {
         if ( IsWindow() )