I did everything as instructed, then at 'make vmlinux' got the following
message, rather quickly (I repeated with newly unpacked source and got the
same):
In file included from /usr/include/errno.h:36
from scripts/split-include.c:26
/usr/include/bits/errno.h:25: linux/errno.h: No such file or directory
make:***[scripts/split-include/ Error 1
What's up with that?