vim-patch:7.4.828

Problem:    Crash when using "syn keyword x c". (Dominique Pelle)
Solution:   Initialize the keyword tabble. (Raymond Ko, PR 397)

670acbc70f

---

see: "fix crash due to hash table not being initialized"
     https://github.com/vim/vim/pull/397

To reproduce:

```sh
nvim -u NONE -c ow -c 'sy keyword x c'
```

src/nvim/version.c

@@ -460,7 +460,7 @@ static int included_patches[] = {
   // 831,
   // 830,
   // 829 NA
-  // 828,
+  828,
   // 827,
   826,
   825,