Use wxFILTER_EXCLUDE_CHAR_LIST in the sample.

It makes more sense than wxFILTER_EXCLUDE_LIST with SetCharExcludes().

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@78142 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775