mount: Remember the extraMounts (and extraMountsEfi, if applicable) in
the global storage (as "extraMounts").
unpackfs: Read the extra mounts from the global storage to generate the
exclude list instead of trying to detect it from the "mount" command's
output, because the latter also includes normally-mounted destination
partitions.
This makes having separate partitions for non-/ mountpoints work again.
Add the following flags to rsync:
* `-H, --hard-links preserve hard links`
* `-A, --acls preserve ACLs (implies --perms)`
* `-X, --xattrs preserve extended attributes`
(i.e., the preservation options not already implied by -a).
Also exclude the special paths that do not make sense to rsync, because
reading the extended attributes from those can cause errors, at least
with SELinux enabled.
This fixes installation of Fedora systems with SELinux enabled.
