cmd/compile: add Type.ChanDir

Generated with eg.

Passes toolstash -cmp.

Change-Id: I3af35191e73a558080f777a4eed93bcec7dfe1f5
Reviewed-on: https://go-review.googlesource.com/21469
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/compile/internal/gc/bexport.go b/src/cmd/compile/internal/gc/bexport.go
index bfa5a50..a63f615 100644
--- a/src/cmd/compile/internal/gc/bexport.go
+++ b/src/cmd/compile/internal/gc/bexport.go
@@ -547,7 +547,7 @@
 
 	case TCHAN:
 		p.tag(chanTag)
-		p.int(int(t.Chan))
+		p.int(int(t.ChanDir()))
 		p.typ(t.Elem())
 
 	default: