incremental builds broken

[ddiss]

The current lkl build logic breaks incremental builds, in that a source change in base kernel won't regenerate tools/lkl/ binaries. This appears to be due to the Makefile dependency chain, where the $(OUTPUT)lib/lkl.o: target is responsible for calling make and make install for the parent base kernel directory.
I've played around with a few hacks to workaround this, but I think the cleanest option might be to conditionally traverse into tools/lkl as part of the regular ARCH=lkl parent kernel build process.

[tavip]

I've played around with a few hacks to workaround this, but I think the cleanest option might be to conditionally traverse into tools/lkl as part of the regular ARCH=lkl parent kernel build process.

This won't work with the current system as we change the kernel config from tools/lkl, so the entry point must be there to make that work.

The current lkl build logic breaks incremental builds, in that a source change in base kernel won't regenerate tools/lkl/ binaries.

This requires calling the kernel build unconditionally for every tools/lkl build. Last time I've looked there was a high cost of doing that, but I'll take another look and see if we can optimize that.