Please support http-client's new h1_client_rustls feature

[joshtriplett]

I'd like to use surf with http-client's new h1_client_rustls feature, so I can avoid openssl. Please consider plumbing that option through as a surf backend feature.

[djarb]

Seconded, thank you.

[Fishrock123]

#271 exists but I am not really sure what the best way to design these feature flags is. Would "h1-rustls-client" be suitable?

[djarb]

That would satisfy my needs

[Fishrock123]

Further discussion exists in #271 (comment)

I also need this for nlopes/libhoney-rust#61

The question is how can the feature flags be structured in a "nice" way. I am not super happy with the http-client h1_client_rustls flag, which is why I had not yet released it. But also, I am not sure if there is presently an alternative since we essentially have a matrix of client+tls feature functionality, and weak dependency features have not yet stabilized.

[joshtriplett]

This seems to be working in the released surf, at this point. While the structure of the feature flags could potentially change in the future, I think this issue as reported has been addressed.

Thank you!