As a performance optimisation, add an explicit check for an empty vector of

timer queues.


[SVN r52291]

libs/asio

@@ -1 +1 @@
-Subproject commit 28e59ef71c005d7ef3f2f8aa9321142e1034cda2
+Subproject commit 5816e90bdbedfe1572b155effe11a3665807e17f