goprotobuf: update for new Set semantics for reflect.Value.

R=rsc
CC=dsymonds, golang-dev
http://codereview.appspot.com/4432051
diff --git a/proto/text_parser.go b/proto/text_parser.go
index ed1cd5c..9463afc 100644
--- a/proto/text_parser.go
+++ b/proto/text_parser.go
@@ -412,7 +412,7 @@
 	case reflect.Ptr:
 		// A basic field (indirected through pointer), or a repeated message/group
 		p.back()
-		fv.Set(reflect.Zero(fv.Type().Elem()).Addr())
+		fv.Set(reflect.New(fv.Type().Elem()))
 		return p.readAny(fv.Elem(), props)
 	case reflect.String:
 		if tok.value[0] == '"' {