pkg/56040: pkgsrc qemu no longer supports nvmm

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         56040
>Category:       pkg
>Synopsis:       pkgsrc qemu no longer supports nvmm
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Mar 05 15:40:01 +0000 2021
>Originator:     Andreas Gustafsson
>Release:        NetBSD 9.0
>Organization:
  
>Environment:
System: NetBSD
Architecture: x86_64
Machine: amd64
>Description:

After updating to the latest pkgsrc, the qemu package no longer
supports nvmm, the NetBSD Virtual Machine Monitor:

  $ qemu-system-x86_64 -accel nvmm
  qemu-system-x86_64: -accel nvmm: invalid accelerator nvmm

The NetBSD project's automated testing infrastructure relies on this
feature.  It works in qemu-5.1.0nb13, but not in qemu-5.2.0.

>How-To-Repeat:

qemu-system-x86_64 -accel nvmm

>Fix: