Problem building x11/nvidia-driver; ref. n245494-6827435548d2

My laptop is currently running main-n245489-15b82e00a164; after updating
sources to n245498-096a84721670, I am performing a source-based update.

A simialr update on my build machine (which is headless, and thus does
not use anything related to X11) was successful.

The laptop is set up to rebuild x11/nvidia-driver when the kernel
is updated.

The buildkernel step on it fails with:

...
awk -f /usr/src/sys/conf/kmod_syms.awk nvidia-modeset.ko  export_syms | xargs -J% objcopy % nvidia-modeset.ko
===> lib (all)
===> lib/libglvnd (all)
...
===> x11/driver (all)
===> x11/extension (all)
===> doc (all)
make[6]: "/usr/share/mk/bsd.man.mk" line 53: Malformed conditional (${MK_MANSPLITPKG} == "no")
make[6]: Fatal errors encountered -- cannot continue
make[6]: stopped in /common/S4/obj/usr/src/amd64.amd64/sys/CANARY/common/ports/x11/nvidia-driver/work/NVIDIA-FreeBSD-x86_64-460.56/doc
*** Error code 1

Stop.


On reviewing the list of files changed in 15b82e00a164..096a84721670, I
note a couple of promising-looking candidates:

 share/mk/bsd.opts.mk                |   1 +
 share/mk/src.opts.mk                |   1 -

Reviewing the commit log for share/mk/bsd.opts.mk, I see that the most
recent entry is:

| commit 6827435548d257c672f934db5c6ff01012d96995
| Author: Jung-uk Kim <jkim_at_FreeBSD.org>
| Date:   Tue Mar 16 14:16:10 2021 -0400
| 
|     pkgbase: Fix building out-of-tree manual pages
|     
|     c7e6cb9e08d6 introduced MK_MANSPLITPKG but it was not available for
|     building out-of-tree manual pages.  For example, x11/nvidia-driver fails
|     with the following error:
|     
|     ===> doc (all)
|     make[3]: "/usr/share/mk/bsd.man.mk" line 53: Malformed conditional (${MK_MANSPLITPKG} == "no")
|     make[3]: Fatal errors encountered -- cannot continue
|     
|     Move the definition from src.opts.mk to bsd.opts.mk to make it visible.

which looks ... apropos.

Indeed, it appears that the n245494-6827435548d2 change was intended to
fix the issue that I am now just seeing.

But I readily confess that I have neither familairity nor expertise
with share/mk/* (and that delving into it reminds me of "You are
in a mazy twist of passages, all different")

So...  help?  What do I need to do to be able to build the kernel now?

(E.g., if I need to just skip building x11/nvidia-driver once, get
everything installed, then build "normally" (with x11/nvidia-driver)
-- that's fine; I just need a clue.)

Thanks.

Peace,
david
-- 
David H. Wolfskill                              david_at_catwhisker.org
That broadly-popular "American Rescue Plan" (stimulus/COVID relrief)?
Ever Republican vote in Congress was against it.

See https://www.catwhisker.org/~david/publickey.gpg for my public key.