Tracking issue for openssl 0.11

[alex]

This will be the next semver-incompatible upgrade. (Note that this will only be the openssl crate, not openssl-sys):

• Upgrade foreign-types: Upgrade ForeignTypes to grab ForeignType::into_ptr #2297
• Drop support for OpenSSL<1.1
• Drop support for older LibreSSL
• Remove openssl::hash in favor of openssl::md and openssl::md_ctx
• Remove openssl::encrypt in favor of openssl::pkey and openssl::pkey_ctx
• Resolve FIXMEs for misc API breaks.
• ...