goprotobuf: Explicitly type the generated enum constants.

R=r
CC=golang-dev
http://codereview.appspot.com/4952045
diff --git a/proto/equal_test.go b/proto/equal_test.go
index 9634771..e22c13b 100644
--- a/proto/equal_test.go
+++ b/proto/equal_test.go
@@ -49,7 +49,7 @@
 	{"equal empty", &pb.GoEnum{}, &pb.GoEnum{}, true},
 
 	{"one set field, one unset field", &pb.GoTestField{Label: String("foo")}, &pb.GoTestField{}, false},
-	{"one set field zero, one unset field", &pb.GoTest{Kind: Int32(0)}, &pb.GoTest{}, false},
+	{"one set field zero, one unset field", &pb.GoTest{Param: Int32(0)}, &pb.GoTest{}, false},
 	{"different set fields", &pb.GoTestField{Label: String("foo")}, &pb.GoTestField{Label: String("bar")}, false},
 	{"equal set", &pb.GoTestField{Label: String("foo")}, &pb.GoTestField{Label: String("foo")}, true},