Isolated emscripten in new lib

lib/emscripten/emtests/test_relocatable_void_function.c

@@ -0,0 +1,17 @@
+/*
+ * Copyright 2016 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 <stdio.h>
+
+void hi_world() {
+  puts("hi world");
+}
+
+int main() {
+  hi_world();
+  return 0;
+}