patch 8.2.3864: cannot disable requesting key codes from xterm

Problem:    Cannot disable requesting key codes from xterm.
Solution:   Add the 'xtermcodes' option, default on.
diff --git a/src/term.c b/src/term.c
index f74b18a..e97ec2c 100644
--- a/src/term.c
+++ b/src/term.c
@@ -4694,7 +4694,7 @@
 
 	// If xterm version >= 141 try to get termcap codes.  For other
 	// terminals the request should be ignored.
-	if (version >= 141)
+	if (version >= 141 && p_xtermcodes)
 	{
 	    LOG_TR(("Enable checking for XT codes"));
 	    check_for_codes = TRUE;
@@ -6446,8 +6446,7 @@
 	    if (name[0] == 'C' && name[1] == 'o')
 	    {
 		// Color count is not a key code.
-		i = atoi((char *)str);
-		may_adjust_color_count(i);
+		may_adjust_color_count(atoi((char *)str));
 	    }
 	    else
 	    {