patch 8.2.0095: cannot specify exit code for :cquit

Problem:    Cannot specify exit code for :cquit.
Solution:   Add optional argument. (Thinca, Yegappan Lakshmanan, closes #5442)
diff --git a/src/testdir/test_quickfix.vim b/src/testdir/test_quickfix.vim
index f7c73f4..b7b4281 100644
--- a/src/testdir/test_quickfix.vim
+++ b/src/testdir/test_quickfix.vim
@@ -4674,4 +4674,29 @@
   call delete('Xtestdir', 'rf')
 endfunc
 
+" Test for :cquit
+func Test_cquit()
+  " Exit Vim with a non-zero value
+  if RunVim([], ["cquit 7"], '')
+    call assert_equal(7, v:shell_error)
+  endif
+
+  if RunVim([], ["50cquit"], '')
+    call assert_equal(50, v:shell_error)
+  endif
+
+  " Exit Vim with default value
+  if RunVim([], ["cquit"], '')
+    call assert_equal(1, v:shell_error)
+  endif
+
+  " Exit Vim with zero value
+  if RunVim([], ["cquit 0"], '')
+    call assert_equal(0, v:shell_error)
+  endif
+
+  " Exit Vim with negative value
+  call assert_fails('-3cquit', 'E16:')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab