tests/unix: Update extra_coverage expected output with new atexit func.

tests/unix/extra_coverage.py.exp

@@ -28,11 +28,11 @@ RuntimeError:
 # repl
 ame__
 
-__class__       __name__        argv            byteorder
-exc_info        exit            getsizeof       implementation
-maxsize         modules         path            platform
-print_exception                 stderr          stdin
-stdout          version         version_info
+__class__       __name__        argv            atexit
+byteorder       exc_info        exit            getsizeof
+implementation  maxsize         modules         path
+platform        print_exception                 stderr
+stdin           stdout          version         version_info
 ementation
 # attrtuple
 (start=1, stop=2, step=3)