vwarn: libc vs opensolaris/ctf/tools

Hello,

Trying to build stable/13 [1] (for ARMv6) if encountered the
following linker error when building cddl/user.bin/ctfdump.

    ld: error: duplicate symbol: vwarn
    >>> defined at utils.c
    >>>            utils.o:(vwarn)
    >>> defined at err.c:148 (/usr/src/lib/libc/gen/err.c:148)
    >>>            err.o:(.text+0x4D0) in archive /usr/lib/libc.a
    cc: error: linker command failed with exit code 1 (use -v to 
    see invocation)

The vwarn function seems to be defined both in lib/libc/gen/err.c
and in cddl/contrib/opensolaris/tools/ctf/common/utils.c. It seems
to be ok to workaround the problem by enclosing OpenSolaris'
implementation in #if 0.

I don't see anything related in my src.conf:

    TARGET=arm
    TARGET_ARCH=armv6
    TARGET_CPUARCH=arm
    TARGET_CPUTYPE=armv6softfp
    
    DESTDIR=/home/stephaner/c/freebsd/dest
    KERNCONF=ARMADA38X
    METALOG=/home/stephaner/c/freebsd/dest/METALOG
    
    # Jan 1, 2030 00:00:00
    BUILD_UTC=1893452400
    DB_FROM_SRC=1
    NO_FSCHG=1
    NO_ROOT=1
    NO_SHARED=1
    NO_RTLD=1
    
    WITHOUT_BEARSSL=1
    WITHOUT_BLUETOOTH=1
    WITHOUT_CAPSICUM=1
    WITHOUT_CASPER=1
    WITHOUT_CFI=1
    WITHOUT_CLEAN=1
    WITHOUT_DEBUG_FILES=1
    WITHOUT_DICT=1
    WITHOUT_GAMES=1
    WITHOUT_GROFF=1
    WITHOUT_KERBEROS=1
    WITHOUT_LIB32=1
    WITHOUT_LLVM_TARGET_ALL=1
    WITHOUT_LOADER_VERIEXEC=1
    WITHOUT_MAIL=1
    WITHOUT_NLS=1
    WITHOUT_OFED=1
    WITHOUT_PROFILE=1
    WITHOUT_SAFESTACK=1
    WITHOUT_TESTS=1
    WITHOUT_VERIEXEC=1
    WITHOUT_WARNS=1
    WITHOUT_WERROR=1
    WITHOUT_ZFS=1
    
    WITH_BIND_NOW=1
    WITH_CLANG=1
    WITH_INSTALL_AS_USER=1
    WITH_PIE=1
    WITH_REPRODUCIBLE_BUILD=1
    WITH_RESCUE=1
    WITH_SHLIBRANDOM=1

Does anyone have a hint or any thing I could investigate?

[1] dd19f0e9c006370d33b56b6d1b66015d7afd00eb

Regards,
-- 
Stéphane Rochoy
O: Stormshield