error building kernel: nfs_clvfsops.o: In function `nfs_mount':, nfs_clvfsops.c:(.text+0x1638): undefined reference to `nfs_diskless_valid'

Since today's source (FreeBSD 9.0-CURRENT/amd64 (source is: Revision: 
221060)  update I get the follwoing error while building the kernel 
(options NFSD/options NFSCL instead of options NFSSERVER/options NFSCLIENT):

cc -c -O2 -frename-registers -pipe -fno-strict-aliasing -march=native 
-std=c99  -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes 
-W issing-prototypes -Wpointer-arith -Winline -Wcast-qual  -Wundef 
-Wno-pointer-sign -fformat-extensions -nostdinc  -I. -I/usr/src/sys 
-I/usr/src/s s/contrib/altq -D_KERNEL -DHAVE_KERNEL_OPTION_HEADERS 
-include opt_global.h -fno-common -finline-limit=8000 --param 
inline-unit-growth=100 --par m large-function-growth=1000 
-fno-omit-frame-pointer -mcmodel=kernel -mno-red-zone  -mfpmath=387 
-mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-ss 3  -msoft-float 
-fno-asynchronous-unwind-tables -ffreestanding -fstack-protector -Werror 
  vers.c
linking kernel
nfs_clvfsops.o: In function `nfs_mount':
nfs_clvfsops.c:(.text+0x1638): undefined reference to `nfs_diskless_valid'
nfs_clvfsops.c:(.text+0x1652): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1658): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1689): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x16d1): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1712): undefined reference to `nfsv3_diskless'
nfs_clvfsops.o:nfs_clvfsops.c:(.text+0x171b): more undefined references 
to `nfsv3_diskless' follow
nfs_clvfsops.o: In function `nfs_mount':
nfs_clvfsops.c:(.text+0x1e19): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e2a): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1e31): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e3d): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e44): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e4a): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e50): undefined reference to `nfs_diskless'
nfs_clvfsops.o:nfs_clvfsops.c:(.text+0x1e57): more undefined references 
to `nfs_diskless' follow
nfs_clvfsops.o: In function `nfs_mount':
nfs_clvfsops.c:(.text+0x1e65): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1e6b): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1e73): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1e79): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1e80): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e87): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e8e): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e94): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1e9a): undefined reference to `nfs_diskless'
nfs_clvfsops.o:nfs_clvfsops.c:(.text+0x1ea0): more undefined references 
to `nfs_diskless' follow
nfs_clvfsops.o: In function `nfs_mount':
nfs_clvfsops.c:(.text+0x1eb3): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1ebd): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1ec4): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1ecb): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1ed2): undefined reference to `nfsv3_diskless'
nfs_clvfsops.o:nfs_clvfsops.c:(.text+0x1ed9): more undefined references 
to `nfsv3_diskless' follow
nfs_clvfsops.o: In function `nfs_mount':
nfs_clvfsops.c:(.text+0x1f18): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1f1e): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1f33): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1f3a): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1f4b): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1f52): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1f5e): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1f6a): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1f71): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1f78): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1f83): undefined reference to `nfs_diskless_valid'
nfs_clvfsops.c:(.text+0x1fcc): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x1fd3): undefined reference to `nfs_diskless'
nfs_clvfsops.c:(.text+0x1fd9): undefined reference to `nfsv3_diskless'
nfs_clvfsops.c:(.text+0x20ae): undefined reference to `nfsv3_diskless'
nfs_clvfsops.o:(.data+0x1f8): undefined reference to `nfsv3_diskless'
nfs_clvfsops.o:(.data+0x258): undefined reference to `nfsv3_diskless'
nfs_clvfsops.o:(.data+0x2b8): undefined reference to `nfs_diskless_valid'
*** Error code 1