No major semantic changes, mostly just deprecations and changed function
signatures. Drop the extra/ patches, as they have been applied upstream.
The added extra/ patch was accepted upstream[0] but has not been picked
up for 5.1. It is required for non-4M aligned backups to work with PBS.
[0] https://lists.gnu.org/archive/html/qemu-devel/2020-08/msg01671.html
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>