Parameterize CircleCI config (#25446)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25446
Parameterize the CircleCI config. So now instead of ~1zillion job specs, there are only a handful, like `pytorch_linux_build` and such. The workflow definition feeds in the appropriate parameters that actually control job behavior.
[Diff](https://gist.github.com/suo/12a48efd36948fc71bdb5c719682a64c) of the `circleci config process` output shows that the actual jobs generated are identical, except for some empty env vars being set.
Differential Revision: D17133395
Test Plan: Imported from OSS
Pulled By: suo
fbshipit-source-id: e6d79268b05c91d5079670992bdf4a99e6dc2807
