[Libguestfs] using SPDX tags in libnbd and/or nbdkit?

[Eric Blake]

As the topic has been coming up in other projects recently (for example, 
see https://gitlab.com/libvirt/libvirt-ci/-/merge_requests/39), should 
we update our files to either add SPDX tags, or even outright condense 
our existing copyright blurbs down to an SPDX tag plus documentation in 
a top-level file?  The former (adding a line) is less problematic, the 
latter definitely requires buy-in from all contributors (although the 
list of contributors is relatively small, so it might be easy enough to 
get such buy-in).

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org