r259031 breaks build on CURRENT

I just tried to build head (r259037) and it stops with the following
messages. This is on amd64 with systems clang. Please let me know, if I
should provide more info, thanks.


[..snip..]
===> usb/run (all)
cc  -O2 -pipe -fno-strict-aliasing -Werror -D_KERNEL -DKLD_MODULE
-nostdinc   -DHAVE_KERNEL_OPTION_HEADERS -include
/usr/obj/usr/src/sys/RHURLIN/opt_global.h -I. -I_at_ -I_at_/contrib/altq
-fno-common  -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer
-I/usr/obj/usr/src/sys/RHURLIN  -mno-aes -mno-avx -mcmodel=kernel
-mno-red-zone -mno-mmx -mno-sse -msoft-float
-fno-asynchronous-unwind-tables -ffreestanding -fstack-protector
-std=iso9899:1999 -Qunused-arguments -fstack-protector -Wall
-Wredundant-decls -Wnested-externs -Wstrict-prototypes
-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual  -Wundef
-Wno-pointer-sign -fformat-extensions  -Wmissing-include-dirs
-fdiagnostics-show-option  -Wno-error-tautological-compare
-Wno-error-empty-body  -Wno-error-parentheses-equality  -c
/usr/src/sys/modules/usb/run/../../../dev/usb/wlan/if_run.c
/usr/src/sys/modules/usb/run/../../../dev/usb/wlan/if_run.c:3233:6:
error: invalid application of 'sizeof' to an
      incomplete type 'struct rt2870_txwi'
            sizeof(struct rt2870_txwi)), rt2860_rates[ridx].rate, qid);
            ^     ~~~~~~~~~~~~~~~~~~~~
_at_/dev/usb/usb_debug.h:41:21: note: expanded from macro 'DPRINTFN'
           __FUNCTION__ ,##__VA_ARGS__);        \
                           ^
/usr/src/sys/modules/usb/run/../../../dev/usb/wlan/if_run.c:3233:20:
note: forward declaration of
      'struct rt2870_txwi'
            sizeof(struct rt2870_txwi)), rt2860_rates[ridx].rate, qid);
                          ^
_at_/dev/usb/usb_debug.h:41:21: note: expanded from macro 'DPRINTFN'
           __FUNCTION__ ,##__VA_ARGS__);        \
                           ^
1 error generated.
*** Error code 1
Stop.
make[5]: stopped in /usr/src/sys/modules/usb/run