Please support Native - TLS and Rust-TLS conditional compilation

[zhuxiujia]

Please support native-tls and rust-tls conditional compilation

• This is because native-tls requires the operating system to install Open-SSL.（The Open-SSL version has serious problems on some cloud service operating systems, Upgrading Open-SSL is not supported）
• But the rust-tls No system dependence whatsoever
• As far as I know, reqwest currently supports conditional compilation switching

[Fishrock123]

There is a PR for this, I just need to actually get to it: #271

It will only be supported for the h1-client.

We don't use reqwest for the hyper-client. It will not support rustls because it uses hyper directly with tls support from hyper-tls which only uses native-tls. If you would like rustls support with hyper please open an issue at https://github.com/hyperium/hyper-tls/issues

[Fishrock123]

The h1-client-rustls support has been merged: #292