Compiles on Windows again.

git-svn-id: http://subversion.jackaudio.org/jack/jack2/trunk/jackmp@3559 0c269be4-1314-0410-8aa9-9f06e86f4224

windows/JackWinNamedPipeServerChannel.h

@@ -27,6 +27,8 @@ Copyright (C) 2004-2006 Grame
 namespace Jack
 {
 
+class JackServer;
+
 class JackClientPipeThread : public JackRunnableInterface
 {