>> У меня компиляция обрывается на i386/boot/boot2. Надо будет попробовать заново перезалить
>> каталог с исходниками. Раз в год обязательно вылезают подобные грабли из-за
>> ошибок синхронизации исходников CVS.
> Это шлангом ?

Вот последние несколько строк вывода:
...
===> sys/boot/i386 (all)
===> sys/boot/i386/mbr (all)
===> sys/boot/i386/pmbr (all)
===> sys/boot/i386/boot0 (all)
===> sys/boot/i386/boot0sio (all)
===> sys/boot/i386/btx (all)
===> sys/boot/i386/btx/btx (all)
===> sys/boot/i386/btx/btxldr (all)
===> sys/boot/i386/btx/lib (all)
===> sys/boot/i386/boot2 (all)
1+0 records in
1+0 records out
512 bytes transferred in 0.000032 secs (16025997 bytes/sec)
cc: warning: the clang compiler does not support '-fno-unit-at-a-time'
In file included from /usr/src/sys/boot/i386/boot2/boot2.c:170:
/usr/src/sys/boot/i386/boot2/../../common/ufsread.c:233:17: warning: cast from
      'char *' to 'struct ufs1_dinode *' increases required alignment from 1 to
      4 [-Wcast-align]
                        memcpy(&dp1, (struct ufs1_dinode *)blkbuf + n,
                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/src/sys/boot/i386/boot2/../../common/ufsread.c:236:17: warning: cast from
      'char *' to 'struct ufs2_dinode *' increases required alignment from 1 to
      4 [-Wcast-align]
                        memcpy(&dp2, (struct ufs2_dinode *)blkbuf + n,
                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/src/sys/boot/i386/boot2/boot2.c:222:1: warning: no previous prototype for
      function 'main' [-Wmissing-prototypes]
main(void)
^
/usr/src/sys/boot/i386/boot2/boot2.c:353:4: warning: cast from 'caddr_t'
      (aka 'char *') to 'Elf32_Word *' (aka 'unsigned int *') increases required
      alignment from 1 to 4 [-Wcast-align]
                *(Elf32_Word *)p = es[i].sh_size;
                 ^~~~~~~~~~~~~~~
/usr/src/sys/boot/i386/boot2/boot2.c:619:8: warning: cast from 'caddr_t'
      (aka 'char *') to 'uint32_t *' (aka 'unsigned int *') increases required
      alignment from 1 to 4 [-Wcast-align]
        t1 = *(uint32_t *)PTOV(0x46c);
              ^~~~~~~~~~~~~~~~~~~~~~~
5 warnings generated.
cc: warning: the clang compiler does not support '-fno-unit-at-a-time'
kernel: ver=1.02 size=690 load=9000 entry=9010 map=16M pgctl=1:1
client: fmt=bin size=1575 text=0 data=0 bss=0 entry=0
output: fmt=bin size=1e05 text=200 data=1c05 org=0 entry=0
-5 bytes available
*** [boot2] Error code 1

Stop in /usr/src/sys/boot/i386/boot2.
*** [all] Error code 1

Stop in /usr/src/sys/boot/i386.
*** [all] Error code 1

Stop in /usr/src/sys/boot.
*** [all] Error code 1

Stop in /usr/src/sys.
*** [sys.all__D] Error code 1

Stop in /usr/src.
*** [everything] Error code 1

Stop in /usr/src.
*** [buildworld] Error code 1

Stop in /usr/src.