Update ninja proto, always enable `ninja -d stats`

The stats output will now use the new "DEBUG" message type, which we can
always redirect to verbose.log.gz.

Test: m aprotoc  (look in verbose.log.gz)
Change-Id: Ie1b58f12c008ff7d29f11ff7a9807488dba8a504
diff --git a/ui/status/ninja.go b/ui/status/ninja.go
index 9cf2f6a..a11774c 100644
--- a/ui/status/ninja.go
+++ b/ui/status/ninja.go
@@ -174,6 +174,8 @@
 				n.status.Print("warning: " + message)
 			case ninja_frontend.Status_Message_ERROR:
 				n.status.Error(message)
+			case ninja_frontend.Status_Message_DEBUG:
+				n.status.Verbose(message)
 			default:
 				n.status.Print(message)
 			}