cp/utils.c:517:14: error: member reference base type 'void' is not a structure or union

Building recent 12-STABLE (revision 365643) for a nanobsd environment
on a CURRENT host fails since a couple of weeks for now with the weird
error shown below. The CURRENT host is running at FreeBSD 13.0-CURRENT
#20 r365382: Fri Sep 11 19:01:26 CEST 2020 amd64. Building 12-STABLE
jails at the very same revision on that CURRENT host with the very same
CURRENT OS revision works fine.

It doesn't help sarting comiling from a clean environment or with a
vanilla (uncustomized) setup for the nanobsd environment.

[...]

/pool/sources/12-STABLE/src/bin/cp/utils.c:517:14: error: member
reference base type 'void' is not a structure or union aclp =
&acl->ats_acl; ~~~^ ~~~~~~~
/pool/sources/12-STABLE/src/bin/cp/utils.c:518:11: error: incomplete
definition of type 'struct acl' if (aclp->acl_cnt != 0 &&
aclsetf(dest_dir, ~~~~^
/pool/sources/12-STABLE/src/bin/cp/utils.c:468:9: note: forward
declaration of 'struct acl' struct acl *aclp;
               ^
2 errors generated.
*** [/pool/sources/12-STABLE/src/bin/cp/utils.o] Error code 1

Kind regards,

oh