Log analysis fails to add backups

[caetanosauer]

Backward log analysis will see the table of backups before the table of mounted volumes, meaning that it will try to redo an sx_add_backup operation on a volume that was not mounted yet. This means that sx_add_backup will see a NULL pointer when getting the volume object.

One possible fix is to simply collect a list of volumes and backups during log analysis, and only apply them in correct order afterwards. I believe Wey uses/used this solution for some operations already.