This inobvious buglet has been spotted shortly after
1.1.0 refactoring was roughly over; the problem is
that armh-specific targets would get ignored without
explicit ARCH=armh.

It's commit 768df7e9
which streamlined introspection within main.mk
and a bug in Makefile which left ARCH empty
even upon having autodetected it for ARCHES.

The current version is more straightforward as a bonus.