Fix SSL errors when using the snapshot Cargo

The second commit message has the details, and these are the relevant external commits:

* https://github.com/alexcrichton/openssl-static-sys/commit/2e1c50a7f35ef52ce38dbd405a175b6dccc0ebad
* https://github.com/alexcrichton/curl-rust/commit/1098e4dd3b89b168b412dfeaba033e41796ea794