Fix make depend error in sys/modules/otus:
$ make depend machine -> /usr/home/lwhsu/work/freebsd-src/head/sys/amd64/include x86 -> /usr/home/lwhsu/work/freebsd-src/head/sys/x86/include :> opt_bus.h :> opt_usb.h awk -f /usr/home/lwhsu/work/freebsd-src/head/sys/modules/otus/../../tools/usbdevs2h.awk /usr/home/lwhsu/work/freebsd-src/head/sys/modules/otus/../../dev/usb/usbdevs -h rm -f .depend mkdep -f .depend -a -nostdinc -D_KERNEL -DKLD_MODULE -I. -I/usr/home/lwhsu/work/freebsd-src/head/sys/modules/otus/../.. -std=iso9899:1999 -std=iso9899:1999 /usr/home/lwhsu/work/freebsd-src/head/sys/modules/otus/../../dev/otus/if_otus.c /usr/home/lwhsu/work/freebsd-src/head/sys/modules/otus/../../dev/otus/if_otus.c:27:10: fatal error: 'opt_wlan.h' file not found #include "opt_wlan.h" ^ 1 error generated. mkdep: compile failed *** Error code 1 Stop. make: stopped in /usr/home/lwhsu/work/freebsd-src/head/sys/modules/otus