* cygheap.h (cwdstuff::drive_length): New member.
(cwdstuff::get_drive): New method.
* path.cc (normalize_win32_path): Simplify by using cwdstuff::get_drive.
(mount_info::conv_to_win32_path): Use cwdstuff::get_drive as default for /.
(cwdstuff::set): Initialize drive_length.