Allow reusing the same wxWindowID more than 254 times.

Extend the id reference count storage to use an overflow hash map for the ids
used more than 254 times. This allows to use the same id an arbitrarily large
number of times.

Closes #13618.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69682 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775