Get amd64 compiling. However, the current kboot supports the only way of
enumerating memory and the new way needs to be incorporated as well. The
powerpc folks can use it.

This commit includes the linker script, trampoline code to start the new
kernel, Linux system calls and the necessary configuration glue needed
to build the binaries.

This includes a quick hack to get multiboot support, but we need to
really share these defines. The multiiboot2.h is the minimum needed to
build.

This should be considered, at best, preliminary.

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