Changed HTTP URLs to HTTPS where possible (#270)

diff --git a/absl/algorithm/container.h b/absl/algorithm/container.h
index 6d5f663..7348d63 100644
--- a/absl/algorithm/container.h
+++ b/absl/algorithm/container.h
@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//      http://www.apache.org/licenses/LICENSE-2.0
+//      https://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,