vim-patch:9.1.0216: Error on exit with EXITFREE and 'winfixbuf' (#28070)

Problem:  Error on exit with EXITFREE and 'winfixbuf'.
Solution: Handle DT_FREE before checking for 'winfixbuf'.
          (zeertzjq)

closes: vim/vim#14314

620e85265c

test/old/testdir/test_winfixbuf.vim

@@ -1,6 +1,7 @@
 " Test 'winfixbuf'
 
 source check.vim
+source shared.vim
 
 " Find the number of open windows in the current tab
 func s:get_windows_count()
@@ -3427,4 +3428,15 @@ func Test_bufdo_cnext_splitwin_fails()
   set winminheight&vim winheight&vim
 endfunc
 
+" Test that exiting with 'winfixbuf' and EXITFREE doesn't cause an error.
+func Test_exitfree_no_error()
+  let lines =<< trim END
+    set winfixbuf
+    qall!
+  END
+  call writefile(lines, 'Xwfb_exitfree', 'D')
+  call assert_notmatch('E1513:',
+        \ system(GetVimCommandClean() .. ' -X -S Xwfb_exitfree'))
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab