patch 9.0.0036: 'fillchars' cannot have window-local values

Problem:    'fillchars' cannot have window-local values.
Solution:   Make 'fillchars' global-local. (closes #5206)
diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index ce60c72..69443c5 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -481,7 +481,7 @@
       call add(total_errors, 'Run ' . g:run_nr . ':')
       call extend(total_errors, v:errors)
 
-      if g:run_nr == 5 || prev_error == v:errors[0]
+      if g:run_nr >= 5 || prev_error == v:errors[0]
         call add(total_errors, 'Flaky test failed too often, giving up')
         let v:errors = total_errors
         break