Fix $(dir /foo) for both C++ and Go
diff --git a/func.cc b/func.cc
index ff18937..531bba4 100644
--- a/func.cc
+++ b/func.cc
@@ -267,8 +267,7 @@
   WordWriter ww(s);
   for (StringPiece tok : WordScanner(*text)) {
     ww.Write(Dirname(tok));
-    if (tok != "/")
-      s->push_back('/');
+    s->push_back('/');
   }
 }