buildworld failed in /usr/src/contrib/groff/src/preproc/eqn/eqn.y and lex.cpp, no such file box.h and eqn_tab.h

[Wang FreeBSD]

I want to migration from FreeBSD 5.2 to FreeBSD RELENG_5.
After using cvsup update source code, I run buildworld.

First time it stop at libstdc++, no unwind.h, I fixed it by modify
Makefile.inc in it.
Second time it stop at libsupc++, fixed it with same way.
Third time, it failed in libgroff, fixed it with same way.

Last time, it reports a strange error message, I don't know how to fix it.

I search on Google, found some people meet the same problem with me in NetBSD.
The answer is got /usr/src/gnu/groff/, make cleandir twice. I don't
know it works or not.

Anyone can help me? Following is the error message:
====================================================================
===> gnu/usr.bin/groff/src/preproc
===> gnu/usr.bin/groff/src/preproc/eqn
yacc -d /usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/eqn.y
mv -f y.tab.c eqn.cpp
mv -f y.tab.h eqn_tab.h
rm -f .depend
mkdep -f .depend -a   
-I/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/include
-I/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../src/include   
eqn.cpp /usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/main.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/lex.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/box.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/limit.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/list.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/over.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/text.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/script.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/mark.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/other.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/delim.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/sqrt.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/pile.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/special.cpp
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/eqn.y:25:17:
box.h: No such file or directory
/usr/src/gnu/usr.bin/groff/src/preproc/eqn/../../../../../../contrib/groff/src/preproc/eqn/lex.cpp:23:21:
eqn_tab.h: No such file or directory
mkdep: compile failed
*** Error code 1

Stop in /usr/src/gnu/usr.bin/groff/src/preproc/eqn.
*** Error code 1

Stop in /usr/src/gnu/usr.bin/groff/src/preproc.
*** Error code 1

Stop in /usr/src/gnu/usr.bin/groff/src.
*** Error code 1

Stop in /usr/src/gnu/usr.bin/groff.
*** Error code 1

Stop in /usr/src/gnu/usr.bin.
*** Error code 1

Stop in /usr/src/gnu.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.
*** Error code 1
================================================================
uname -a
FreeBSD alan.jane.net 5.2.1-RELEASE FreeBSD 5.2.1-RELEASE #0: Mon Feb
23 20:45:55 GMT 2004
root at wv1u.btc.adaptec.com:/usr/obj/usr/src/sys/GENERIC  i386
================================================
/etc/make.conf

CPUTYPE=i686
CFLAGS= -O -pipe
CXXFLAGS= -O -pipe
#CXFLAGS+= -fmemoize-lookups -fsave-memoized
COPTFLAGS= -O -pipe
#WANT_FORCE_OPTIMIZATION_DOWNGRADE=1

NO_FORTRAN=     true
NO_I4B  =       true
NO_IPFILTER=    true
NO_LPR  =       true
NO_OBJC =       true
NO_SENDMAIL=    true
NOGAMES =       true
NO_MAILWRAPPER= true