Replace http://mirror.bazel.build with https://mirror.bazel.build

PiperOrigin-RevId: 172816169
diff --git a/WORKSPACE b/WORKSPACE
index 1bf1069..b409138 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -5,7 +5,7 @@
     sha256 = "110fe68753413777944b473c25eed6368c4a0487cee23a7bac1b13cc49d3e257",
     strip_prefix = "rules_closure-4af89ef1db659eb41f110df189b67d4cf14073e1",
     urls = [
-        "http://mirror.bazel.build/github.com/bazelbuild/rules_closure/archive/4af89ef1db659eb41f110df189b67d4cf14073e1.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_closure/archive/4af89ef1db659eb41f110df189b67d4cf14073e1.tar.gz",
         "https://github.com/bazelbuild/rules_closure/archive/4af89ef1db659eb41f110df189b67d4cf14073e1.tar.gz",  # 2017-08-28
     ],
 )