prevent atexit functions from adding new atexit functions * interpreter.h, interpreter.cc (interpreter::m_executing_atexit): New member variable. (interpreter::execute_atexit_fcns): Set m_executing_atexit to TRUE. (interpreter::add_atexit_fcn): Don't add function to list if executing atexit functions.

--- a/libinterp/corefcn/interpreter.h	Thu Nov 14 15:18:15 2019 -0500
+++ b/libinterp/corefcn/interpreter.h	Thu Nov 14 15:21:49 2019 -0500
@@ -556,6 +556,8 @@
 
     bool m_executing_finish_script;
 
+    bool m_executing_atexit;
+
     bool m_initialized;
 
     void maximum_braindamage (void);