Updating submodules
Updating submodules

Summary:
GitHub commits:

https://github.com/facebook/folly/commit/b3a645ee04660b472af47b09c64ca37d94099e72
https://github.com/facebook/watchman/commit/e378a921919163aec1a2db8cb51a9553fdc109eb
https://github.com/facebookincubator/mvfst/commit/a3788b036bbfe210f675029621fc1f8ede0f0f1c

Reviewed By: wittgenst

fbshipit-source-id: b46cebddb66fc274b7150eeaf4fa771a852cb1c4

facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst