from sources of yesterday, lsof build fails thusly

cc -O2  -DNETBSDV=1060 -DHASGETBOOTFILE -DHASNFSPROTO -DHASIPv6 -DHASFDESCFS=1 -DHASFDLINK -DHASNULLFS -DHASPROCFS -DHAS9660FS -DHASMSDOSFS -DHASKERNFS -DHASNCVPID -DHASI_FFS -DHASEXT2FS -DHASI_E2FS -DHASNFSVATTRP -DUVM -I/home/pkgsrc/sysutils/lsof/work/lsof_4.64/lsof_4.64_src/dialects/n+obsd/include -DHAS_UVM_INCL -DHAS_ADVLOCK_ARGS -DHASCWDINFO -DHAS_SYS_PIPEH -DLSOF_VSTR=\"1.6G\" -I/usr/include -I/sys -O  -c dvch.c
In file included from ../dlsof.h:176,
                 from ../lsof.h:172,
                 from dvch.c:43:
/usr/include/ufs/mfs/mfsnode.h:47: field `mfs_buflist' has incomplete type
*** Error code 1

because struct mfsnod has the member

        struct  bufq_state mfs_buflist; /* list of I/O requests */

defined in sys/buf.h and enclosed in _KERNEL.  is it proper to define
_KERNEL in a user util to get to these definitions?