[help] rebuild libc failed

[majia gm]

Hi, everyone.

I'm building the libc code which derived from a current trunk
mirror/freebsd/head under PCBSD 8.2 which contains FreeBSD 8.2
release.
I'm trying to test the modified libc by using LD_LIBRARY_PATH. But
failed to build it.
I change the current direcotry into head/lib/libc and run make. I get
the following error.

Warning: Object directory not changed from original
/usr/home/forandom/work/soc2011/xxp-head/lib/libc
cc -O2 -pipe  -I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/include
-I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/../../include
-I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/i386 -DNLS
-D__DBINTERFACE_PRIVATE
-I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/../../contrib/gdtoa
-DINET6 -I/usr/home/forandom/work/soc2011/xxp-head/lib/libc
-I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/resolv
-D_ACL_PRIVATE -DPOSIX_MISTAKE
-I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/../../contrib/tzcode/stdtime
-I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/stdtime
-I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/locale
-DBROKEN_DES -DPORTMAP -DDES_BUILTIN
-I/usr/home/forandom/work/soc2011/xxp-head/lib/libc/rpc -DYP
-DNS_CACHING -DSYMBOL_VERSIONING -std=gnu99 -fstack-protector
-Wsystem-headers -Werror -Wall -Wno-format-y2k -Wno-uninitialized
-Wno-pointer-sign -c
/usr/home/forandom/work/soc2011/xxp-head/lib/libc/gen/__getosreldate.c
/usr/home/forandom/work/soc2011/xxp-head/lib/libc/gen/__getosreldate.c:
In function '__getosreldate':
/usr/home/forandom/work/soc2011/xxp-head/lib/libc/gen/__getosreldate.c:58:
error: 'AT_OSRELDATE' undeclared (first use in this function)
/usr/home/forandom/work/soc2011/xxp-head/lib/libc/gen/__getosreldate.c:58:
error: (Each undeclared identifier is reported only once
/usr/home/forandom/work/soc2011/xxp-head/lib/libc/gen/__getosreldate.c:58:
error: for each function it appears in.)
*** Error code 1
Stop in /usr/home/forandom/work/soc2011/xxp-head/lib/libc.

It seems there's little difference between head and this release.
AT_OSRELDATE is defined in head/sys/i386/include/elf.h. But in the
release 8.2, elf.h doesn't have this definition.
How can let it to use the include files in head rather than the system
include files?

Thanks.