Steps for building the 64-bit version of SML/NJ

  1) build the runtime system

	% cd base/runtime/objs
	% make -f mk.amd64-darwin  -- if macOS, or
	  % make -f mk.amd64-linux  -- if linux (e.g. Ubuntu)
	% mv run.amd64-darwin ../../../bin/.run/

  2) cross compile

	% cd ../../system
	% ./cmb-cross amd64-unix

  3) bootstrap

	% ./makeml -64

  4) to test

	% ./testml -64

  5) to install in the bin directory

 	% ./installml -64
