patch 9.0.0801: the modifyOtherKeys flag is set when it should not

Problem:    The modifyOtherKeys flag is set when it should not.
Solution:   Do not handle special key codes with a modifer value above 16 as a
            modifyOtherKeys value. (issue #11403)

src/term.c

@@ -5045,8 +5045,11 @@ handle_csi(
     // Key with modifier:
     //	{lead}27;{modifier};{key}~
     //	{lead}{key};{modifier}u
-    else if ((arg[0] == 27 && argc == 3 && trail == '~')
+    // Only handles four modifiers, this won't work if the modifier value is
+    // more than 16.
+    else if (((arg[0] == 27 && argc == 3 && trail == '~')
 		|| (argc == 2 && trail == 'u'))
+	    && arg[1] <= 16)
     {
 	return len + handle_key_with_modifier(arg, trail,
 			    csi_len, offset, buf, bufsize, buflen);

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    801,
 /**/
     800,
 /**/