qxl in COLO secondary node cause QEMU to segmentation fault
Description of problem:
After COLO checkpoint, the Secondary VM's qemu received segmentation fault while releasing qxl resources in interface_release_resource() routine.     
i have used gdb and qemu trace to debug Secondary VM's qemu. the object 'qxl->last_release' is null and object 'ring->items[prod].el' != 0, it leads to null pointer dereference.     
During COLO checkpoint,the Secondary VM's qemu has loaded Primary VM's qxl states,so i think it not need to release qxl resources.
Steps to reproduce:
1.Startup Primary VM and Secondary VM of COLO mode, and gdb to Secondary VM's qemu.     
2.Connect to Primary VM's spice server.         
3.Secondary VM's qemu will receiveing segmentation fault.
Additional information:
gdb to Secondary VM's qemu:     
   ``` 
Program received signal SIGSEGV, Segmentation fault.      
[Switching to Thread 0x7ff9e3bff700 (LWP 44703)]     
0x0000555555b2e8d6 in interface_release_resource (sin=0x555557d7c8a8, ext=...) at ../hw/display/qxl.c:783     
783	        qxl->last_release->next = ext.info->id;    
(gdb) bt   
#0  0x0000555555b2e8d6 in interface_release_resource (sin=0x555557d7c8a8, ext=...) at ../hw/display/qxl.c:783    
#1  0x00007fffd7751dd1 in red_drawable_unref () at /lib64/libspice-server.so.1    
#2  0x00007fffd771eabe in drawable_unref () at /lib64/libspice-server.so.1    
#3  0x00007fffd77206a7 in draw_until () at /lib64/libspice-server.so.1   
#4  0x00007fffd771f7cd in display_channel_draw () at /lib64/libspice-server.so.1   
#5  0x00007fffd7721b51 in display_channel_process_draw () at /lib64/libspice-server.so.1   
#6  0x00007fffd7752142 in red_process_display () at /lib64/libspice-server.so.1
#7  0x00007fffd77521fb in worker_source_dispatch () at /lib64/libspice-server.so.1
#8  0x00007fffd6c2f049 in g_main_context_dispatch () at /lib64/libglib-2.0.so.0
#9  0x00007fffd6c2f3a8 in g_main_context_iterate.isra.19 () at /lib64/libglib-2.0.so.0
#10 0x00007fffd6c2f67a in g_main_loop_run () at /lib64/libglib-2.0.so.0
#11 0x00007fffd775166a in red_worker_main () at /lib64/libspice-server.so.1
#12 0x00007fffd5658dd5 in start_thread () at /lib64/libpthread.so.0
#13 0x00007fffd538202d in clone () at /lib64/libc.so.6
(gdb) frame 0
#0  0x0000555555b2e8d6 in interface_release_resource (sin=0x555557d7c8a8, ext=...) at ../hw/display/qxl.c:783
783	        qxl->last_release->next = ext.info->id;
(gdb) print qxl->last_release
$1 = (QXLReleaseInfo *) 0x0
   ```

qemu trace log:
   ```
44840@1643012769.363844:colo_send_message Send 'checkpoint-reply' message
44840@1643012773.579053:colo_receive_message Receive 'vmstate-send' message
44840@1643012773.978838:colo_receive_message Receive 'vmstate-size' message
44840@1643012773.979041:colo_send_message Send 'vmstate-received' message
44840@1643012774.180598:qxl_pre_load 0
44703@1643012774.180660:qxl_ring_res_put 0 #res=20
44840@1643012774.182627:qxl_post_load 0 native
44840@1643012774.197993:colo_vm_state_change Change 'stop' => 'run'
44840@1643012774.198030:colo_send_message Send 'vmstate-loaded' message
   ```