patch 8.2.4866: duplicate code in "get" functions

Problem:    Duplicate code in "get" functions.
Solution:   Use get_var_from() for getwinvar(), gettabvar(), gettabwinvar()
            and getbufvar(). (closes #10335)

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4866,
 /**/
     4865,
 /**/