patch 8.0.0289: no test for "ga" and :ascii

Problem:    No test for "ga" and :ascii.
Solution:   Add a test. (Dominique Pelle, closes #1429)
diff --git a/src/testdir/test_alot.vim b/src/testdir/test_alot.vim
index 2b163ae..38b9f7a 100644
--- a/src/testdir/test_alot.vim
+++ b/src/testdir/test_alot.vim
@@ -19,6 +19,7 @@
 source test_fnamemodify.vim
 source test_functions.vim
 source test_glob2regpat.vim
+source test_ga.vim
 source test_goto.vim
 source test_help_tagjump.vim
 source test_join.vim