(mount_info::conv_to_win32_path): Eliminate now-unneeded relative path name arg
and processing.
(path_conv::check): Accomodate relative path names again. Accomodate one extra
argument in mount_info::conv_to_win32_path. Tack trailing slash on end of
relative path as a side effect, like before.
* shared_info.h (mount_info::conv_to_win32_path): Reflect new argument
ordering.