bhyve/virtio-scsi: fix sign-compare warning on gcc15

[siva]

Summary

In file included from /usr/src/usr.sbin/bhyve/pci_emul.h:41,

from /usr/src/usr.sbin/bhyve/pci_virtio_scsi.c:64:

/usr/src/usr.sbin/bhyve/pci_virtio_scsi.c: In function 'pci_vtscsi_queue_request':
/usr/src/usr.sbin/bhyve/pci_virtio_scsi.c:671:40: error: comparison of integer expressions of different signedness: 'ssize_t' {aka 'long int'} and 'long unsigned int' [-Werror=sign-compare]

671 |             (void **)&req->vsr_cmd_rd) == VTSCSI_IN_HEADER_LEN(q->vsq_sc));

Fixes: 2a514d377b37a30356c5c27a07b4fb0fd6df4881

[jhb]

Sigh, this is kind of terrible. Code that is required should never be invoked as part of assert(). Your change is correct, but I think style-wise it is better to declare bufsize at the start of the function instead of creating a nested block.

[siva]

Thanks, abandoning this review in favour of D55800 and D55803 by the author then.