patch 9.1.0232: Conceal test fails when rightleft feature is disabled

Problem:  Conceal test fails when rightleft feature is disabled.
Solution: Skip test if rightleft feature is missing (Julio B).

closes: #14342

Signed-off-by: Julio B <julio.bacel@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_conceal.vim b/src/testdir/test_conceal.vim
index 355817d..2ce7384 100644
--- a/src/testdir/test_conceal.vim
+++ b/src/testdir/test_conceal.vim
@@ -199,6 +199,7 @@
 
 " Same as Test_conceal_wrapped_cursorline_wincolor(), but with 'rightleft'.
 func Test_conceal_wrapped_cursorline_wincolor_rightleft()
+  CheckFeature rightleft
   CheckScreendump
 
   let code =<< trim [CODE]