[coreboot] Buildrom lzma patch and update QEMU Config-lab.lb

[Myles Watson]

These patches go together and make it so that checking the "USE_LZMA"
option in buildrom doesn't break builds.

It assumes that all Config.lb files don't use compression, and all
Config-lab.lb files do.

The qemu-lab.lzma.diff patch makes that change.

Signed-off-by: Myles Watson

Thanks,
Myles