BINOWN or BINGRP. Otherwise manual pages and documentation installed
from the same directories as suid or sgid programs will have incorrect
user or group ownership. (Uucico manpage owned by uucp, su manpage owned
by root, etc.)
Use bsd.subdir.mk for building subdirectories.
Don't forget to remove x.cc and x.C when using SHAREDSTRINGS.
Make ${PROG} always depend on ${LIBCRT0}.
Don't duplicate code between cleandir and clean.
Move tags target to bsd.dep.mk.
Move STRIP to bsd.own.mk.
Remove redundant definitions of {BIN,MAN}{DIR,GRP,OWN,MODE}.
Move {LIB,DOC}{DIR,GRP,OWN,MODE} defaults to bsd.own.mk.