go-winio now defines this function, so we can consume that.
Note that there's a difference between the old implementation and the original
one (added in 1cb9e9b44e). The old implementation
had special handling for win32 error codes, which was removed in the go-winio
implementation in 0966e1ad56
As `go-winio.GetFileSystemType()` calls `filepath.VolumeName(path)` internally,
this patch also removes the `string(home[0])`, which is redundant, and could
potentially panic if an empty string would be passed.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>