patch 8.2.0520: tests are not listed in sorted order

Problem:    Tests are not listed in sorted order.
Solution:   Move test_ex_mode. (Doug Richardson, closes #5889)
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index 1a47cfc..8ca7831 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -96,9 +96,9 @@
 	test_escaped_glob \
 	test_eval_stuff \
 	test_ex_equal \
+	test_ex_mode \
 	test_ex_undo \
 	test_ex_z \
-	test_ex_mode \
 	test_excmd \
 	test_exec_while_if \
 	test_execute_func \