Target generation is revised, split into $YTARG and $TARG.
$PROGS is inlined to the cmd target.
%.cpus is added to allow chaining: mk all.cpus
$POWERLESS is added, since dtracy doesn't build yet on ppc.
$DIRS regexp is simplified, simplifing $NOMK.
$cpuobjtype is replaced with cp's recipe for copying itself on $cputype.
$APEDIRS is removed.
The none target is renamed to usage, since it prints out usage.
The ape target is removed.
The dirs target is replaced by all.dirs
%.directories is replaced by %.dirs
The all target serializes directories after cmds to match the install target recipe.
All regexp rules are replaced with nonregexp versions for clarity.
The &:n: rule is removed. Just build the $O.$cmd file.
.y files now build .c files, not .tab.c files, and remove (bc|units|mpc|pc).c:R:
All safeinstall rules are removed.
The cleanfiles rule is renamed to cleancmds and simplified.
%.clean is removed. Just use mk cleancmds.
The install rule serializes cp and yacc before building anything else, avoiding races.
The installall recipe is simplified with the install.cpus prereq.
%.installall is removed. Just use mk $cmd.install.cpus
The $O.cj, %.update, and compilers rules are removed.
