CPU: Add a comment

src/ngraph/runtime/cpu/external_function.cpp

@@ -183,6 +183,11 @@ void ExternalFunction::compile()
     Emitter emitter;
     codegen::CodeWriter& TU = emitter.get_code_writer();
 
+    // The "dso_handle" symbol below is required by __cxa_atexit()
+    // which is enabled because the JIT uses it as the default mechanism
+    // to register cleanup handlers. We use it, and not atexit(), because
+    // atexit() happens too late, when the JIT is no longer alive
+
     TU +=
         R"(// Generated by the NGraph CPU backend
 #include <cmath>