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/test72.in b/src/testdir/test72.in
index a407eea..961df4c 100644
--- a/src/testdir/test72.in
+++ b/src/testdir/test72.in
@@ -4,6 +4,7 @@
 
 STARTTEST
 :so small.vim
+:set belloff=all
 :"
 :" Test 'undofile': first a simple one-line change.
 :set nocompatible viminfo+=nviminfo visualbell
@@ -25,7 +26,6 @@
 :set undofile
 :bwipe!
 :e Xtestfile
-:" TODO: this beeps
 u:.w >>test.out
 :"
 :" Test 'undofile', add 10 lines, delete 6 lines, undo 3