r362666 breaking buildworld (don't know how to make nvpair.c) & Fix/Patch

[Enji Cooper]

(Moving hackers to BCC since the issue is current-related)

> On Jun 26, 2020, at 6:56 PM, Neel Chauhan <neel at neelc.org> wrote:
> 
> Hi,
> 
> When I attempt to build world in 13-CURRENT, I get this error:

…

> The build broke with mmacy@'s commit r362666 which renamed nvpair.c to bsd_nvpair.c without renaming the Makefile.

...

Hi Neel,
	It looks like the issue was recently fixed in r362669 by mmacy.
Cheers!
-Enji