Don't exclude "contrib" from wxMSW setup.exe generation.

Don't exclude "contrib" from wxMSW setup.exe generation.

This was presumably needed to exclude the top level contrib directory but also
seems to apply to src/tiff/contrib and excluding this directory breaks
configuration of libtiff as it looks for src/tiff/contrib/Makefile.in.

As we don't even have top level contrib any more, simply don't exclude it any
longer.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65482 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775