At some point, I'm going to commit a libdrm package to wip based upon
development sources--but don't hold your breath. ;)

I will look into this when I have time, but could you try building it
with current sources?  It will _probably_ work with NetBSD's drm, but
I'm not positive as I haven't looked into what the nv driver requires
as I don't have the hardware.  I'm going to begin updating our
kernel's DRM bit by bit
soon, also.

Please do file a PR so I can keep track of this, especially if you
still have no success building the driver.

Regards,

--Blair