add patch to avoid huge snapshot performance regression

Taking a snapshot became prohibitively slow because of the
migration_transferred_bytes() call in migration_rate_exceeded() [0].

This also applied to the async snapshot taking in Proxmox VE, so
work around the issue until it is fixed upstream.

[0]: https://gitlab.com/qemu-project/qemu/-/issues/1821

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

debian/patches/series

@@ -4,6 +4,7 @@ extra/0003-ide-avoid-potential-deadlock-when-draining-during-tr.patch
 extra/0004-migration-block-dirty-bitmap-fix-loading-bitmap-when.patch
 extra/0005-hw-ide-reset-cancel-async-DMA-operation-before-reset.patch
 extra/0006-Revert-Revert-graph-lock-Disable-locking-for-now.patch
+extra/0007-migration-states-workaround-snapshot-performance-reg.patch
 bitmap-mirror/0001-drive-mirror-add-support-for-sync-bitmap-mode-never.patch
 bitmap-mirror/0002-drive-mirror-add-support-for-conditional-and-always-.patch
 bitmap-mirror/0003-mirror-add-check-for-bitmap-mode-without-bitmap.patch