daemon: Close augeas, hivex, journal handles in unmount_all.

This is also called implicitly from internal_autosync, ensuring that
exit won't fail because of an open handle.

libguestfs: error: internal_autosync: umount: /sysroot: umount: /sysroot: target is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))