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/build/ninja.go b/ui/build/ninja.go
index 1b13e5d..fa44cb1 100644
--- a/ui/build/ninja.go
+++ b/ui/build/ninja.go
@@ -39,6 +39,7 @@
 	args := []string{
 		"-d", "keepdepfile",
 		"-d", "keeprsp",
+		"-d", "stats",
 		"--frontend_file", fifo,
 	}