Finish restructuring 'libraries' example

[SVN r26855]

v2/example/libraries/util/foo/Jamfile

@@ -0,0 +1,5 @@
+
+project 
+    : usage-requirements <include>include ;
+
+lib bar : bar.cpp ;

v2/example/libraries/util/foo/bar.cpp

@@ -0,0 +1,13 @@
+//  Copyright (c) 2003 Vladimir Prus
+//
+//  Distributed under the Boost Software License, Version 1.0. (See
+//  accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//
+//  http://www.boost.org
+// 
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+void foo() {};