buildworld failure

Building /usr/obj/usr/src/amd64.amd64/tools/build/test-includes/sys_bitcount.c
Building /usr/obj/usr/src/amd64.amd64/tools/build/test-includes/sys_bitcount.o
sys_bitcount.c:1:10: fatal error: 'sys/bitcount.h' file not found
#include <sys/bitcount.h>
         ^~~~~~~~~~~~~~~~
1 error generated.
*** Error code 1

Stop.
make[3]: stopped in /usr/src/tools/build/test-includes
.ERROR_TARGET='sys_bitcount.o'
.ERROR_META_FILE='/usr/obj/usr/src/amd64.amd64/tools/build/test-includes/sys_bitcount.o.meta'
.MAKE.LEVEL='3'
MAKEFILE=''
.MAKE.MODE='meta missing-filemon=yes missing-meta=yes silent=yes verbose'
_ERROR_CMD='/usr/local/bin/clang14  -O2 -pipe -fno-common   -g -gz=zlib -std=gnu99 -Wno-format-zero-length -nobuiltininc -idirafter /usr/local/llvm14/lib/clang/14.0.6/include -fstack-protector-strong -Wsystem-headers -Werror -Wall -Wno-format-y2k -W -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow -Wunused-parameter -Wcast-align -Wchar-subscripts -Wnested-externs -Wold-style-definition -Wno-pointer-sign -Wdate-time -Wmissing-variable-declarations -Wthread-safety -Wno-empty-body -Wno-string-plus-int -Wno-unused-const-variable -Wno-error=unused-but-set-variable  -Qunused-arguments    -c sys_bitcount.c -o sys_bitcount.o; ;'
.CURDIR='/usr/src/tools/build/test-includes'
.MAKE='make'
.OBJDIR='/usr/obj/usr/src/amd64.amd64/tools/build/test-includes'
.TARGETS='test-includes'
DESTDIR='/usr/obj/usr/src/amd64.amd64/tmp'
LD_LIBRARY_PATH=''
MACHINE='amd64'
MACHINE_ARCH='amd64'
MAKEOBJDIRPREFIX=''
MAKESYSPATH='/usr/src/share/mk'
MAKE_VERSION='20220208'
PATH='/usr/obj/usr/src/amd64.amd64/tmp/bin:/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:/usr/obj/usr/src/amd64.amd64/tmp/legacy/usr/libexec::/usr/obj/usr/src/amd64.amd64/tmp/bin:/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:/usr/obj/usr/src/amd64.amd64/tmp/legacy/usr/libexec::/sbin:/bin:/usr/sbin:/usr/bin'
SRCTOP='/usr/src'
OBJTOP='/usr/obj/usr/src/amd64.amd64
.....................................

Anyone see/know anything causing this error? 
Also, the buildworld command most likely to build the most amd64 components from scratch?