make: verify that default cross-compile value is actually valid, add another cross-compiler option for x86_64
make: verify that default cross-compile value is actually valid
And error out with a clear message to the user if that's not the case.
make: add another cross-compiler option for x86_64
On Fedora, the cross-compiler doesn't have the -pc
part.
I hadn't cross-compiled a kernel in a long time, and I had forgotten about CROSS_COMPILE
and it took me too long to figure out what I did wrong, so let's verify our defaults and give clear error messages for the next person