fix(package.accept_keywords) add ~amd64 to efitools and gnu-efi

This is required for these packages to build as upstream has not
stabilized them yet, and it's doubtful that will happen any year soon...
fix(package.accept_keywords) put back ChromiumOS copyright.

I was wrong to remove it, oops.
Merge pull request #190 from gregkh/new_keywords

fix(package.accept_keywords) add ~amd64 to efitools and gnu-efi