Merge from trunk:

* Instead of using tie(), set the ios_base::unitbuf flag to force the stream to be flushed after every insertion. Fixes #7162


[SVN r79712]

libs/asio

@@ -1 +1 @@
-Subproject commit a37edb5c8426a3d5fa98e15e2aeac5255495dc0b
+Subproject commit f88a411217bd7ac360daef70953036dbf977e385