Update nccl submodule to 2.4.2 (#17883)
Summary:
Didn't test this. Let's see what happens.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17883
Differential Revision: D14547470
Pulled By: pietern
fbshipit-source-id: c35d232f6bcc5a2dce55da636a0acbea5c2725d8
