test(old): add some missing tests from Vim patches 8.1.2320 and 8.1.2360

src/nvim/testdir/test_quickfix.vim

@@ -2020,6 +2020,7 @@ func s:test_xgrep(cchar)
   enew
   set makeef=Temp_File_##
   silent Xgrepadd GrepAdd_Test_Text: test_quickfix.vim
+  call assert_true(len(g:Xgetlist()) == 9)
 
   " Try with 'grepprg' set to 'internal'
   set grepprg=internal
@@ -2739,6 +2740,25 @@ func Test_cwindow_jump()
   call assert_true(winnr('$') == 2)
   call assert_true(winnr() == 1)
 
+  " open the quickfix buffer in two windows and jump to an entry. Should open
+  " the file in the first quickfix window.
+  enew | only
+  copen
+  let bnum = bufnr('')
+  exe 'sbuffer ' . bnum
+  wincmd b
+  cfirst
+  call assert_equal(2, winnr())
+  call assert_equal('F1', bufname(''))
+  enew | only
+  exe 'sb' bnum
+  exe 'botright sb' bnum
+  wincmd t
+  clast
+  call assert_equal(2, winnr())
+  call assert_equal('quickfix', getwinvar(1, '&buftype'))
+  call assert_equal('quickfix', getwinvar(3, '&buftype'))
+
   " Jumping to a file from the location list window should find a usable
   " window by wrapping around the window list.
   enew | only