r355097 make buildkernel: ports module graphics/gpu-firmware-kmod (all): could not find bsd.sysdir.mk

The tail of my most recent run of

make -j2 buildkernel KERNCONF=GENERIC-NODEBUG

===> Ports module graphics/gpu-firmware-kmod (all)
cd ${PORTSDIR:-/usr/ports}/graphics/gpu-firmware-kmod; env  -u CC -u 
CXX  -u CPP  -u MAKESYSPATH  -u MK_AUTO_OBJ  -u MAKEOBJDIR MAKEFLAGS="-j 
2 -J 15,16 -j 2 -J 15,16 -D NO_MODULES_OBJ .MAKE.LEVEL.ENV=MAKELEVEL 
KERNCONF=GENERIC-NODEBUG KERNEL=kernel TARGET=amd64 TARGET_ARCH=amd64"  
SYSDIR=/usr/src/sys 
PATH=/usr/obj/usr/src/amd64.amd64/tmp/usr/sbin:/usr/obj/usr/src/amd64.amd64/tmp/usr/bin:/usr/obj/usr/src/amd64.amd64/tmp/legacy/usr/sbin:/usr/obj/usr/src/amd64.amd64/tmp/legacy/usr/bin:/usr/obj/usr/src/amd64.amd64/tmp/legacy/bin::/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:/usr/local/sbin 
SRC_BASE=/usr/src  OSVERSION=1300060 
WRKDIRPREFIX=/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG make -B 
clean build
===>  Cleaning for gpu-firmware-kmod-g20191015
===>  License AMD INTEL accepted by the user
===>   gpu-firmware-kmod-g20191015 depends on file: /usr/local/sbin/pkg 
- found
===> Fetching all distfiles required by gpu-firmware-kmod-g20191015 for 
building
===>  Extracting for gpu-firmware-kmod-g20191015
=> SHA256 Checksum OK for 
FreeBSDDesktop-kms-firmware-g20191015-81315fa_GH0.tar.gz.
===>  Patching for gpu-firmware-kmod-g20191015
===>  Configuring for gpu-firmware-kmod-g20191015
===>  Building for gpu-firmware-kmod-g20191015
===> i915kmsfw (all)
===> i915kmsfw/bxtdmc (all)
make[6]: "/usr/src/sys/conf/kmod.mk" line 77: Could not find bsd.sysdir.mk
make[6]: Fatal errors encountered -- cannot continue
make[6]: stopped in 
/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG/usr/ports/graphics/gpu-firmware-kmod/work/kms-firmware-81315fa/i915kmsfw/bxtdmc
*** Error code 1

Stop.
make[5]: stopped in 
/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG/usr/ports/graphics/gpu-firmware-kmod/work/kms-firmware-81315fa/i915kmsfw
*** Error code 1

Stop.
make[4]: stopped in 
/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG/usr/ports/graphics/gpu-firmware-kmod/work/kms-firmware-81315fa
===> Compilation failed unexpectedly.
Try to set MAKE_JOBS_UNSAFE=yes and rebuild before reporting the failure to
the maintainer.
*** Error code 1

Stop.
make[3]: stopped in /usr/ports/graphics/gpu-firmware-kmod
*** [all] Error code 1

make[2]: stopped in /usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG
1 error

make[2]: stopped in /usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG
*** [buildkernel] Error code 2

make[1]: stopped in /usr/src
1 error

make[1]: stopped in /usr/src
*** [buildkernel] Error code 2

make: stopped in /usr/src
1 error

make: stopped in /usr/src
root_at_momh167-gjp4-8570p:/usr/src #

----

Environment:

# date ; uname -v
Tue Nov 26 04:38:41 GMT 2019
FreeBSD 13.0-CURRENT #37 r354945: Thu Nov 21 19:11:47 GMT 2019 
root_at_momh167-gjp4-8570p:/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG
# bectl list
BE       Active Mountpoint Space Created
r350684  -      -          1.66M 2019-08-07 19:01
r354082b -      -          108G  2019-10-27 14:08
r354616b -      -          1.37M 2019-11-16 17:35
r354945  -      -          1.29M 2019-11-21 13:06
r354945a -      -          1.39M 2019-11-22 02:26
r354945b -      -          1.61M 2019-11-25 06:04
r355097  NR     /          25.7G 2019-11-25 19:16
#