Isolated emscripten in new lib

lib/emscripten/emtests/test_random_device.cpp

@@ -0,0 +1,21 @@
+// Copyright 2014 The Emscripten Authors.  All rights reserved.
+// Emscripten is available under two separate licenses, the MIT license and the
+// University of Illinois/NCSA Open Source License.  Both these licenses can be
+// found in the LICENSE file.
+
+#include <random>
+#include <iostream>
+#include <exception>
+
+auto main()
+  -> int
+try
+{
+  std::random_device rd;
+  std::cout << "random was read" << "\n";
+}
+catch( const std::exception& e )
+{
+  std::cerr << e.what();
+}
+