blkid: use list_for_each_safe in garbage collection

We need to use list_for_each_safe in case a device gets removed from
the list during garbage collection.

Also make the manpage slightly more informative about
what the -g garbage collection option does.

Addresses-Debian-Bug: #487758, #487783

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2 files changed