Don't consider extra ".." an error in wxFileName::Normalize().

Don't consider extra ".." an error in wxFileName::Normalize().

The path being normalized could have come from user and there doesn't seem to
be any point in complaining about too many ".."s in it when we can handle them
correctly instead.

So simply ignore the extra ".."s for the absolute paths and keep them
unchanged for the relative ones instead of returning an error.

See #10960.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66218 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775