patch 8.0.0737: crash when X11 selection is very big

Problem:    Crash when X11 selection is very big.
Solution:   Use static items instead of allocating them.  Add callbacks.
            (Ozaki Kiichi)
diff --git a/src/testdir/test_quotestar.vim b/src/testdir/test_quotestar.vim
index b053260..b7d3158 100644
--- a/src/testdir/test_quotestar.vim
+++ b/src/testdir/test_quotestar.vim
@@ -88,6 +88,18 @@
   call WaitFor('@* == "yes"')
   call assert_equal('yes', @*)
 
+  " Handle the large selection over 262040 byte.
+  let length = 262044
+  let sample = 'a' . repeat('b', length - 2) . 'c'
+  let @* = sample
+  call WaitFor('remote_expr("' . name . '", "len(@*) >= ' . length . '", "", 1)', 3000)
+  let res = remote_expr(name, "@*", "", 2)
+  call assert_equal(length, len(res))
+  " Check length to prevent a large amount of output at assertion failure.
+  if length == len(res)
+    call assert_equal(sample, res)
+  endif
+
   if has('unix') && has('gui') && !has('gui_running')
     let @* = ''