umh build...

Alexei, I tried to build bpfilter on sparc64 and it shows that
CONFIG_OUTPUT_FORMAT is an x86 specific Kconfig value.

And, even if I added it, it's not clear what it should even be set to.

Right now, for example, my userland builds default to 32-bit sparc
even though I'm building a 64-bit kernel.

I think what ends up happening has to be in some way in response to
what kind of "native" binaries HOSTCC is actually building.