Fix a deadlock that can occur when destroying a thread object with global

lifetime in a dynamically loaded DLL on Windows. Note that deadlock can
still occur if the thread is launched by the constructor of an object with
global lifetime.


[SVN r45935]

libs/asio

@@ -1 +1 @@
-Subproject commit 56b93eea3a34c2c57c3092f10a93fc13d52b813e
+Subproject commit f3ee6627d852df4019327c026818803f3e429b69