Upgrade bazlets to latest stable-2.16 to build with 2.16 API

Change-Id: Ib17bbec712bf0bd1806181f19efbe543c5222a3f
diff --git a/WORKSPACE b/WORKSPACE
index 9d5a331..2a44119 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "d044cd60d37e302d9ac324f7a2c4e48b4011d4e6",
+    commit = "c2227415d5044f8439bd47edffb0f052f8da2ac5",
 )
 
 # Snapshot Plugin API