Merge fixes from trunk:

* Fix bullet list.

* Fix include guard.

* Zero-length reads and writes need to complete immediately.

* Fix for static mutex initialisation.

Authorized by Beman


[SVN r72847]

libs/asio

@@ -1 +1 @@
-Subproject commit 7d6c1c318dcc95c1f1bcaf2a6ffb52c9d8edc7d0
+Subproject commit 18a48222edeef468b6f5cb0663e687fda9123657