(slightly modified to unconditionally add the relative path to the subdir)

Rusty Russel wrote:

"M-x compile" in emacs stars a compilation and can jump to the next
error.  With KBUILD_VERSBOSE=0 (as I have in my env, great work Kai)
it can't figure out the directory, since it doesn't see the make[XXX]
markers.

This makes it work.