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_normal.vim b/src/testdir/test_normal.vim
index 3af79f8..e0df0ae 100644
--- a/src/testdir/test_normal.vim
+++ b/src/testdir/test_normal.vim
@@ -1,5 +1,6 @@
 " Test for various Normal mode commands
 
+set belloff=all
 func! Setup_NewWindow()
   10new
   call setline(1, range(1,100))