[io] fix read offset in RRawFileWin.cxx
[io] fix read offset in RRawFileWin.cxx

olifre/root,root-mirror/root,olifre/root,root-mirror/root,karies/root,root-mirror/root,karies/root,olifre/root,karies/root,karies/root,olifre/root,root-mirror/root,karies/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,karies/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,karies/root,olifre/root,karies/root,olifre/root,karies/root,karies/root