cmd/compile: update some type names in comments

Change-Id: I741a1205bc6256c08b36efed43652bfbb75e4401
Reviewed-on: https://go-review.googlesource.com/19691
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/compile/internal/gc/go.go b/src/cmd/compile/internal/gc/go.go
index 7cfc2c9..13a28c8 100644
--- a/src/cmd/compile/internal/gc/go.go
+++ b/src/cmd/compile/internal/gc/go.go
@@ -329,8 +329,7 @@
 
 const (
 	// types of channel
-	// must match ../../pkg/nreflect/type.go:/Chandir
-	Cxxx  = 0
+	// must match ../../../../reflect/type.go:/ChanDir
 	Crecv = 1 << 0
 	Csend = 1 << 1
 	Cboth = Crecv | Csend