Fix IAM role URL to not require a redirect.
Fix IAM role URL to not require a redirect.

With the tokio refactor, we switched to async Hyper for fetching AWS
credentials, and Hyper no longer supports automatically following
HTTP redirects.

mozilla/sccache,glandium/sccache,mozilla/sccache,mozilla/sccache,luser/sccache2,luser/sccache2,glandium/sccache,luser/sccache2,luser/sccache2,glandium/sccache,glandium/sccache