pick fix for potential deadlock with QMP resize and iothread

While the patch gives bdrv_graph_wrlock() as an example where the
issue can manifest, something similar can happen even when that is
disabled. Was able to reproduce the issue with
while true; do qm resize 115 scsi0 +4M; sleep 1; done
while running
fio --name=make-mirror-work --size=100M --direct=1 --rw=randwrite \
 --bs=4k --ioengine=psync --numjobs=5 --runtime=1200 --time_based
in the VM.

Fix picked up from:
https://lists.nongnu.org/archive/html/qemu-devel/2023-12/msg01102.html

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>

debian/patches/bitmap-mirror/0006-mirror-move-some-checks-to-qmp.patch

@@ -62,10 +62,10 @@ index 00f2665ca4..60cf574de5 100644
  
          if (bitmap_mode != BITMAP_SYNC_MODE_NEVER) {
 diff --git a/blockdev.c b/blockdev.c
-index 83d5cc1e49..060d86a65f 100644
+index 01b0ab0549..cd5f205ad1 100644
 --- a/blockdev.c
 +++ b/blockdev.c
-@@ -2924,7 +2924,36 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
+@@ -2925,7 +2925,36 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
          sync = MIRROR_SYNC_MODE_FULL;
      }