add arg.h and util.h to Makefile

Makefile

@@ -18,7 +18,7 @@ options:
 	@echo CC $<
 	@${CC} -c ${CFLAGS} $<
 
-${OBJ}: config.h config.mk
+${OBJ}: config.h config.mk arg.h util.h
 
 config.h:
 	@echo creating $@ from config.def.h
@@ -35,8 +35,8 @@ clean:
 dist: clean
 	@echo creating dist tarball
 	@mkdir -p slock-${VERSION}
-	@cp -R LICENSE Makefile README config.def.h config.mk ${SRC} \
+	@cp -R LICENSE Makefile README slock.1 config.mk \
-		explicit_bzero.c slock.1 slock-${VERSION}
+		${SRC} explicit_bzero.c config.def.h arg.h util.h slock-${VERSION}
 	@tar -cf slock-${VERSION}.tar slock-${VERSION}
 	@gzip slock-${VERSION}.tar
 	@rm -rf slock-${VERSION}