patch 9.1.0185: 'wincolor' hl missing with 'rightleft', "below" virttext, 'nowrap'

Problem:  'wincolor' highlight missing with 'rightleft', "below" virtual
          text and 'nowrap'.
Solution: Handle 'rightleft' in draw_screen_line() (zeertzjq).

closes: #14216

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_textprop.vim b/src/testdir/test_textprop.vim
index 993a64d..c88b547 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -4535,6 +4535,11 @@
   call term_sendkeys(buf, 'k')
   call VerifyScreenDump(buf, 'Test_prop_wincolor_8', {})
 
+  if has('rightleft')
+    call term_sendkeys(buf, ":set rightleft\<CR>:\<CR>")
+    call VerifyScreenDump(buf, 'Test_prop_wincolor_9', {})
+  endif
+
   call StopVimInTerminal(buf)
 endfunc