rio&nudraw: make cleanlier

mkfile

@@ -1,6 +1,6 @@
 </$objtype/mkfile
 BIN=$home/bin/$objtype
-
+PWD=`{pwd}
 TARG=rio
 OFILES=\
 	rio.$O\
@@ -18,8 +18,17 @@ HFILES=dat.h\
 
 </sys/src/cmd/mkone
 
-$O.out:	`{pwd}/nudraw/libnudraw.a /$objtype/lib/libframe.a \
+$PWD/nudraw/libnudraw.a:
+	cd nudraw
+	mk
+
+$O.out:	$PWD/nudraw/libnudraw.a /$objtype/lib/libframe.a \
 	/$objtype/lib/libthread.a /$objtype/lib/libplumb.a /$objtype/lib/libc.a
 syms:V:
 	$CC -a $CFLAGS rio.c	> syms
 	$CC -aa $CFLAGS *.c 	>>syms
+
+clean:V:
+	rm -f *.[OS] [$OS].out
+	cd nudraw
+	mk clean