Bump ffi to 0c8364a728cfe4e4ba859c53b99d56b3dbe3add4

Changes:
```
> git log --format="%C(auto) %h %s" 4dd3242..0c8364a
 https://dart.googlesource.com/ffi.git/+/0c8364a Update README.md (#143)
 https://dart.googlesource.com/ffi.git/+/fea40a9 Revert "Common C integer types (#128)" (#141)
 https://dart.googlesource.com/ffi.git/+/c4c59e8 Update pubspec.yaml (#139)
 https://dart.googlesource.com/ffi.git/+/d81d1b7 Bump version to 1.2.0 (#132)
 https://dart.googlesource.com/ffi.git/+/5a33a25 Enable and fix new strict analysis options (#131)
 https://dart.googlesource.com/ffi.git/+/5e801e8 Common C integer types (#128)

```

Diff: https://dart.googlesource.com/ffi.git/+/4dd32429880a57b64edaf54c9d5af8a9fa9a4ffb~..0c8364a728cfe4e4ba859c53b99d56b3dbe3add4/
Change-Id: Ie1d3e30030594a24fdece7408ae3687033f8e772
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/244963
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Commit-Queue: Devon Carew <devoncarew@google.com>

DEPS

@@ -108,7 +108,7 @@ vars = {
 
   "dartdoc_rev": "334072b0cad436c05f6bcecf8a1a59f2f0809b84",
   "devtools_rev": "3c16b8d73120e46958982d94215d499793b972eb",
-  "ffi_rev": "4dd32429880a57b64edaf54c9d5af8a9fa9a4ffb",
+  "ffi_rev": "0c8364a728cfe4e4ba859c53b99d56b3dbe3add4",
   "file_rev": "0132eeedea2933513bf230513a766a8baeab0c4f",
   "fixnum_rev": "3bfc2ed1eea7e7acb79ad4f17392f92c816fc5ce",
   "glob_rev": "e10eb2407c58427144004458ef85c9bbf7286e56",