make buildkernel doesn't

Hi,

fbsd 13-current r346053 amd64

make buildkernel fails near the start here:

awk -f /usr/src/sys/tools/usbdevs2h.awk /usr/src/sys/dev/usb/usbdevs -d
--- genoffset.o ---
cc: error: no such file or directory: 'FLAGS'
*** [genoffset.o] Error code 1

more detail at
https://rpi3.zyxst.net/errors/13-current/r346053/20190409-kernbuildfail.txt

thanks,
-- 
J.