x86 vm fails to stop on Darwin aarch64 when qemu compiled with -O1/-O2
Description of problem:
When compiled with `-O2` or `-O1` qemu process hangs on full VM stopping on macOS aarch64 host if `shutdown -P now` initiated from guest system.
Steps to reproduce:
1. Compile latest qemu version with -O2 (default value) or -O1 passed 
2. Run qemu-system-x86_64 with ubuntu image, e.g. https://cloud-images.ubuntu.com/focal/20230215/focal-server-cloudimg-amd64.img and custom cloud-init (for user/password authentication)
3. Wait until image is loaded, connect via vnc or provide login/password in stdio
4. Initiate shutdown with `sudo shutdown -P now`
5. See that VM indefinitely shutdowns
6. Kill VM from host system with kill -9 <qemu-system-x86_64-process-pid>
7. Recompile qemu with -O0
8. Repeat steps 2-4
9. See that vm successfully stopped, and qemu process exited with code 0
Additional information:
I've created thread dump from activity monitor with threads which qemu hanging on, attached below
[sample-qemu-system-x86_64.txt](/uploads/119b89b7f55f4374acb9ae1f9dc2e517/sample-qemu-system-x86_64.txt)

Probably there is some compiler optimisation which prevents qemu threads from receive shutdown signal or appropriate notification from another threads.

The compiler version with which qemu is built:
```bash
% cc --version
Apple clang version 14.0.3 (clang-1403.0.22.14.1)
Target: arm64-apple-darwin22.4.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
```