astutil: move to go/ast/astutil

Change-Id: I9a45bfc07613eb2210081d306d71f0a4d152eda5
Reviewed-on: https://go-review.googlesource.com/2592
Reviewed-by: Alan Donovan <adonovan@google.com>
diff --git a/refactor/satisfy/find.go b/refactor/satisfy/find.go
index 2af37f1..9770a02 100644
--- a/refactor/satisfy/find.go
+++ b/refactor/satisfy/find.go
@@ -49,7 +49,7 @@
 	"go/ast"
 	"go/token"
 
-	"golang.org/x/tools/astutil"
+	"golang.org/x/tools/go/ast/astutil"
 	"golang.org/x/tools/go/types"
 )