qemu-system-i386 no longer boots NetBSD
Description of problem:
Since qemu commit b56617bbcb473c25815d1bf475e326f84563b1de, qemu-system-i386 can no longer boot NetBSD.
Steps to reproduce:
```
wget https://cdn.netbsd.org/pub/NetBSD/NetBSD-10.0/images/NetBSD-10.0-i386.iso
qemu-system-i386 -cdrom NetBSD-10.0-i386.iso
```

Expected behavior: Boots into the NetBSD installer

Observed incorrect behavior: Boot hangs with a black screen
Additional information:
This regression is a critical issue to the NetBSD project as its automated testing infrastructure is heavily dependent on qemu-system-i386.