qcow2: Make qcow2_write_snapshots() public

Updating the snapshot list will be useful when upgrading a v2 image to
v3, so we will need to call this function in qcow2.c.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-6-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2 files changed