We are promising more than just odd fixes, and Paolo is hoping
to offload the pull requests to me.  Also, enough of NBD is related
to the block layer that it is worth including qemu-block on patches.

While at it, include blockdev-nbd.c and qemu-nbd.texi in the set
of maintained files.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170707182151.29872-1-eblake@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>