[coreboot] SeaBIOS CPP definition

[Myles Watson]

I'm not sure if it's buildrom's fault or SeaBIOS's, but the build
fails for me with this error:

make[1]: P: Command not found

It's actually a symptom that $(CPP) isn't being set.  When I add these
lines in SeaBIOS's Makefile, it goes away.

ifeq ($(CPP),)
CPP=$(CC) -E
endif

Where should it get fixed?

Thanks,
Myles