[Bug-tar] tar doesn't handle some tarballs created under Microsoft Windows

[Ali Sabil]

Hello,

I would like to report that GNU Tar, doesn't handle some tarball containing \ as directory separator created
under Microsoft Windows.

Currently, it will extract a folder, with the correct content and everything inside being correct, but it will
also create folders with \ in their names :

$ tar xjvf DirectX90c.tar.bz2 
DirectX90c.DevPackage
DirectX90c
DirectX90c\\Common\\
DirectX90c\\DLL\\
DirectX90c\\docs\\
DirectX90c\\Icons\\
DirectX90c\\include\\
DirectX90c\\lib\\
DirectX90c\\Templates\\
DirectX90c/Common/dxstdafx.cpp
DirectX90c/Common/dxstdafx.h
...