Add make target to check if toolchain is up to date
Various automated build/test services use a specific toolchain build for all tests, and have no way to know if the toolchain has been updated and requires a rebuild. This, in turn, means manual intervention is needed for these services every time the toolchain version changes. (unless various hacks involving searching the output text are used, but these are highly suboptimal).
A new make target to check if the built toolchain is completely up to date with the current coreboot versions would be very useful.