OSS: upgrade Folly 2016.09.26 => 2016.10.31

Summary:
There was a fix around folly::dynamic constructor that will be needed for Fabric work. This was done in https://github.com/facebook/folly/commit/94e964976c1b65e79b0f7bdd960cfec260399a52#diff-7d1cb97d222ba0c863ea8a8e43b2ee2b and luckily the release 1 month after the Folly version we used in RN already had the fix, so that we don't need to upgrade to the latest folly yet (minimizing breakages).

Tested by:
* running RNTester xcode project (ios)
* running RNTesterPods workspace via cocoapods
* building android via gradle

Reviewed By: shergin

Differential Revision: D7626037

fbshipit-source-id: cb36ba5b91ba131d4e450300bd620db657cfa1e8