diff CHANGELOG @ 528:db2cd87cef6f c++11-mutex

This will be v2.9

--- a/CHANGELOG	Wed Sep 11 14:55:16 2019 +0100
+++ b/CHANGELOG	Tue Oct 22 12:10:41 2019 +0100
@@ -1,3 +1,19 @@
+
+Version 2.9, 2019-10-23 (maintenance release)
+
+  * Fix non-thread-safe behaviour in PluginAdapter. Plugins built
+    using the adapter classes in version 2.8 or earlier cannot safely
+    be used simultaneously across threads with other instances of
+    themselves or of other plugins in the same library (i.e. shared
+    object). Hosts have been required to provide synchronisation for
+    such cases. Version 2.9 introduces synchronisation in the plugin,
+    making this usage safe. Unfortunately this does not make host code
+    safe when using older plugin builds, as the problem and its fix
+    are in the plugin side of the SDK. Caution is still required, but
+    this fix does allow updated plugin builds to avoid problems with
+    some existing hosts
+  * Change required C++ language standard from C++98 to C++11. This
+    is because of the use of std::mutex in the above fix
 
 Version 2.8, 2019-02-07 (maintenance and minor feature release)