Upgrade bazlets to latest stable-2.16

- download_file.py: Synchronize curl options with gerrit core
- Bazel: Make build tool chain forward compatible

Change-Id: Ic57b35e489a4a95a2e8a259741c79d38ba657047

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 6ea3990..3894b61 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "8105536e13d04c7c595a56ce21867471ce47b36d",
+    commit = "62b278c85340707cf9f73df4127a9263ac5628c5",
     #local_path = "/home/<user>/projects/bazlets",
 )