patch 9.1.0801: tests: no error check when setting global 'termwinkey'

Problem:  tests: no error check when setting global 'termwinkey'
Solution: Also validate when using setglobal (Milly).

closes: #15917

Signed-off-by: Milly <milly.ca@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: Milly

src/optionstr.c

@@ -3892,9 +3892,11 @@ did_set_term_option(optset_T *args)
  * The 'termwinkey' option is changed.
  */
     char *
-did_set_termwinkey(optset_T *args UNUSED)
+did_set_termwinkey(optset_T *args)
 {
-    if (*curwin->w_p_twk != NUL && string_to_key(curwin->w_p_twk, TRUE) == 0)
+    char_u	**varp = (char_u **)args->os_varp;
+
+    if ((*varp)[0] != NUL && string_to_key(*varp, TRUE) == 0)
 	return e_invalid_argument;
 
     return NULL;

src/testdir/gen_opt_test.vim

@@ -56,7 +56,6 @@ let skip_setglobal_reasons = #{
       \ shiftwidth:	'TODO: fix missing error handling for setglobal',
       \ sidescrolloff:	'TODO: fix missing error handling for setglobal',
       \ tabstop:	'TODO: fix missing error handling for setglobal',
-      \ termwinkey:	'TODO: fix missing error handling for setglobal',
       \ textwidth:	'TODO: fix missing error handling for setglobal',
       \}
 

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    801,
 /**/
     800,
 /**/