patch 8.2.0775: not easy to call a Vim function from Lua

Problem:    Not easy to call a Vim function from Lua.
Solution:   Add vim.call() and vim.fn(). (Prabir Shrestha, closes #6063)

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    775,
 /**/
     774,
 /**/