venti: use 9ar, not ar (fixes Darwin build problem)
diff --git a/src/cmd/venti/srv/mkfile b/src/cmd/venti/srv/mkfile
index dc54187..4ff8bb0 100644
--- a/src/cmd/venti/srv/mkfile
+++ b/src/cmd/venti/srv/mkfile
@@ -77,7 +77,7 @@
 <$PLAN9/src/mkmany
 
 $SLIB: $LIBOFILES
-	ar rvc $SLIB $LIBOFILES
+	9ar rvc $SLIB $LIBOFILES
 
 # xml.c:D:	mkxml dat.h
 # 	./mkxml dat.h > xml.c