Demos: Add "DynamicObjectDemo" to demo the dynamic loader

Author: https://github.com/itamar8910
Commit: 09ccdc697b
Pull-request: https://github.com/SerenityOS/serenity/pull/3738
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/awesomekling

Demos/DynamicObject/SampleLib/lib.cpp

@@ -0,0 +1,20 @@
+
+#include "../lib.h"
+
+int func();
+
+__thread int g_tls1 = 0;
+__thread int g_tls2 = 0;
+
+static void init_function() __attribute__((constructor));
+
+void init_function()
+{
+    g_tls1 = 1;
+    g_tls2 = 2;
+}
+
+int func()
+{
+    return 3;
+}