Various GRUB utilities fail if the current directory doesn't exist,
because grub_find_device() chdirs to a different directory and then
fails when trying to chdir back. Gnulib's save-cwd module uses fchdir()
instead when it can, avoiding this category of problem.
Fixes Debian bug #918700.
Signed-off-by: Colin Watson <cjwatson@ubuntu.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>