patch 8.0.0433: beeps when running tests

Problem:    Quite a few beeps when running tests.
Solution:   Set 'belloff' for these tests. (Christian Brabandt)
diff --git a/src/testdir/test_close_count.in b/src/testdir/test_close_count.in
index f07da99..f40fd23 100644
--- a/src/testdir/test_close_count.in
+++ b/src/testdir/test_close_count.in
@@ -2,6 +2,7 @@
 
 STARTTEST
 :so small.vim
+:set belloff=all
 :let tests = []
 :for i in range(5)
 :new