From: Jiri Benc on
gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/2490#note_1409...
That looks much better. And yes, I think it's something for upstream.
IMHO Documentation/kbuild/kbuild.rst documents HOSTCFLAGS as something that
can be overriden from the make command line. Anything in kernel makefiles that
breaks that is thus a bug.