patch 9.1.0572: cannot specify tab page closing behaviour

Problem:  cannot specify tab page closing behaviour
          (Gianluca Pacchiella)
Solution: Add the 'tabclose' option (LemonBoy).

fixes: #5967
closes: #15204

Signed-off-by: LemonBoy <thatlemon@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/gen_opt_test.vim b/src/testdir/gen_opt_test.vim
index 8cca2b9..7674714 100644
--- a/src/testdir/gen_opt_test.vim
+++ b/src/testdir/gen_opt_test.vim
@@ -144,6 +144,7 @@
       \ 'splitkeep': [['cursor', 'screen', 'topline'], ['xxx']],
       \ 'swapsync': [['', 'sync', 'fsync'], ['xxx']],
       \ 'switchbuf': [['', 'useopen', 'split,newtab'], ['xxx']],
+      \ 'tabclose': [['', 'left', 'left,uselast'], ['xxx']],
       \ 'tagcase': [['smart', 'match'], ['', 'xxx', 'smart,match']],
       \ 'term': [[], []],
       \ 'termguicolors': [[], []],