Cross compilation doesn't work with 0.15.1 enabling reqwest/native-tls by default

[jqnatividad]

Hello @Stranger6667 , enabling reqwest/native-tls by default to fix #343 causes cross-compilation to fail as native-tls depends on openssl and cross no longer bundles openssl (cross-rs/cross#229).

Would it be possible to have another feature to use rustls in addition to the current resolve-http feature, as cross compiles work with it, i.e.

resolve-http-rustls = ["reqwest", "rustls"]