cmd/compile/internal/gc: unexport and make Hasdefer a bool

Passes go build -a -toolexec 'toolstash -cmp' std cmd.

Change-Id: I804ee4252fa9be78cb277faf7f467e6c9cfdd4a6
Reviewed-on: https://go-review.googlesource.com/14319
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index 38e22fc..4a79b66 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -231,7 +231,7 @@
 		walkstmt(&n.Right)
 
 	case ODEFER:
-		Hasdefer = 1
+		hasdefer = true
 		switch n.Left.Op {
 		case OPRINT, OPRINTN:
 			walkprintfunc(&n.Left, &n.Ninit)