Upgrade bazlets to latest stable-2.16 to build with 2.16.26 API

Change-Id: Ie6445fc9cfa52d7bef988f00ed9256ec51ace585

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index add9251..58ce94b 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "7be854b98543c6429dd5038ff38846a1230b4dbe",
+    commit = "6c39deb06f58bb62162ccb6865964f531739f512",
     #local_path = "/home/<user>/projects/bazlets",
 )