Forbid creation of wxStandardPaths object directly.

This happens to work under MSW and Unix where there is only one
wxStandardPaths class for both the console and the GUI applications but
doesn't return the correct result under OS X where the Core Foundation
version, returned by wxStandardPaths::Get(), has to be used for the GUI
programs. And historically this confused a lot of people, so just ensure that
they can't accidentally create an object of the wrong type any more.

Closes #13537.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74428 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -408,6 +408,10 @@ Changes in behaviour which may result in compilation errors
   any more. Use wxBookCtrlEvent in your code if you need to forward-declare
   it or just include the appropriate header instead of forward declaration.
 
+- wxStandardPaths class can't be created now. This was never the right thing
+  to do, wxStandardPaths::Get() always had to be used to access the global
+  object of the correct type but now doing it results in a compilation error.
+
 
 Deprecated methods and their replacements
 -----------------------------------------