Added build option for the nested kernel.
Added protected CPU functionality interface to the nested kernel.

These are all in sys/nk/ but there should be some sepeartion of the functions
so that the external code can only link in and call the nk_ functions. The
build system will need to be updated later.

The functionality in this:
    - Nested calls for updating: cr0, cr3, cr4, and MSRs
    - Internal functionality for updating.
Added the nested kernel to CSOPE build dirs
Added a new conf file to the amd64 branch, and also included the nk_cpufunc.c
file to the build files. At this point the nk file will build and is ready for
servicing external calls.
Converted the first load_cr4 function to the nk version.
Skeleton files for the virtual MMU interface and backend physical MMU update
functionality for the nested kernel.