make XPM data pointer parameter fully const

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@51211 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/icon.h

@@ -27,8 +27,10 @@ class WXDLLIMPEXP_CORE wxIcon: public wxBitmap
 public:
     wxIcon();
 
-    wxIcon( const char **bits, int width=-1, int height=-1 );
-    wxIcon( char **bits, int width=-1, int height=-1 );
+    wxIcon(const char* const* bits);
+#ifdef wxNEEDS_CHARPP
+    wxIcon(char **bits);
+#endif
 
     // For compatibility with wxMSW where desired size is sometimes required to
     // distinguish between multiple icons in a resource.