freebsd stable - Jul 2019 - Updating from 11.2p10 to p11 fails to builld /sbin/rescue on DIR_ROUNDUP

Hello all,

In the course of updating from FreeBSD 11.2p10 to p11, we receive the
following error message from buildworld:

clang -O2 -pipe -I/usr/src/sbin/fsck_ffs -I/usr/src/sbin/mount
-DRESCUE -MD  -MF.depend.dir.o -MTdir.o -std=gnu99
-fstack-protector-strong -Wsystem-headers -Werror -Wall
-Wno-format-y2k -Wno-uninitialized -Wno-pointer-sign -Wno-empty-body
-Wno-string-plus-int -Wno-unused-const-variable
-Wno-tautological-compare -Wno-unused-value -Wno-parentheses-equality
-Wno-unused-function -Wno-enum-conversion -Wno-unused-local-typedef
-Wno-address-of-packed-member -Wno-switch -Wno-switch-enum
-Wno-knr-promoted-parameter  -Qunused-arguments  -c
/usr/src/sbin/fsck_ffs/dir.c -o dir.o
/usr/src/sbin/fsck_ffs/dir.c:237:23: error: use of undeclared identifier
      'DIR_ROUNDUP'
            (dp->d_reclen & (DIR_ROUNDUP - 1)) != 0)
                             ^
/usr/src/sbin/fsck_ffs/dir.c:285:33: error: use of undeclared identifier
      'DIR_ROUNDUP'
                unused = roundup2(namlen + 1, DIR_ROUNDUP) - (namlen + 1);
                                              ^
/usr/src/sbin/fsck_ffs/dir.c:285:33: error: use of undeclared identifier
      'DIR_ROUNDUP'
3 errors generated.
*** Error code 1

Stop.
make[6]: stopped in /usr/src/sbin/fsck_ffs
*** Error code 1

Stop.
make[5]: stopped in /usr/obj/usr/src/rescue/rescue
*** Error code 1

Stop.
make[4]: stopped in /usr/src/rescue/rescue
*** Error code 1

Stop.
make[3]: stopped in /usr/src/rescue
*** Error code 1

Stop.
make[2]: stopped in /usr/src
*** Error code 1

Stop.
make[1]: stopped in /usr/src
*** Error code 1

Stop.
make: stopped in /usr/src

There's nothing in UPDATING about this, and 11.3 builds OK on the same
platform.

Did I miss or forget a step?

Thanks for any advice!