USETOOLS=yes friendly):
since the file only changes when a new bootxx.raw is committed into this
directory, commit a generated version of macppcboot.raw here as well.
clean up the framework that builds mkmacppcboot as well, and don't
remove macppcboot.raw on make clean.
rough at this point, and needs more fleshing out in several areas. Does not
yet do packages or check for the existence of support programs--to be fixed.