building 8.2 toolchain on 10.1: redefinition of le{16,32,64}dec

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

I'm trying to build a 8.2 toolchain on a 10.1 host and I get lots of errors

/usr/src-8/tools/libctf/../compat/compat_defs.h:1100:22: error: redefinition of 'le16enc'
 1100 | __GEN_ENDIAN_ENC(16, le)
      |                      ^~
/usr/src-8/tools/libctf/../compat/compat_defs.h:1085:1: note: in definition of macro '__GEN_ENDIAN_ENC'
 1085 | endian ## bits ## enc(void *dst, uint ## bits ## _t u) \
      | ^~~~~~
In file included from /usr/include/amd64/endian.h:3,
                 from /usr/src-8/tools/libctf/../../external/cddl/osnet/sys/machine/endian.h:32,
                 from /usr/include/sys/types.h:98,
                 from /usr/src-8/tools/libctf/../../external/cddl/osnet/sys/sys/types.h:77,
                 from /usr/src-8/tools/libctf/../compat/compat_defs.h:35,
                 from /var/work/obj-8/tooldir.NetBSD-10.1-amd64/include/compat/nbtool_config.h:871,
                 from /usr/src-8/tools/libctf/../../external/cddl/osnet/dist/common/ctf/ctf_types.c:23:
/usr/include/sys/endian.h:210:1: note: previous definition of 'le16enc' was here
  210 | __GEN_ENDIAN_ENC(16, le)
      | ^~~~~~~~~~~~~~~~
In file included from /var/work/obj-8/tooldir.NetBSD-10.1-amd64/include/compat/nbtool_config.h:871,
                 from /usr/src-8/tools/libctf/../../external/cddl/osnet/dist/common/ctf/ctf_types.c:23:

and the like.

command is build.sh -j 10 -U -O /var/work/obj-8 release.

Am I doing something stupidly wrong?