patch 8.2.1772: cannot use CTRL-W <Down> to move out of a terminal window

Problem:    Cannot use CTRL-W <Down> to move out of a terminal window.
Solution:   Use special_to_buf() instead of mb_char2bytes(). (closes #7045)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1772,
 /**/
     1771,
 /**/