encoding the relative path.
This means that the kernel can be totally self contained now and is not dependent on the last buildworld to update /usr/share/mk. This might also make it easier to build 5.x kernels on 4.0 boxes etc, assuming gensetdefs and config(8) are updated.
and empty options files. The rules are now generated automatically in bsd.kmod.mk. Cleaned up related things ($S and ${CLEANFILES}).
