std.fs.path: revert recent public API change

41fd343508880ffdfbc83c7b053237da09199f02 made a breaking change to the
public API; this commit reverts the API changes but keeps the
improved logic.
3d89ff5130Andrew Kelley committed on 1/11/2022, 6:00:19 PMparentb65a884
2 files changedLine totals unavailable