Feature flag for flate2 on ratchet-deflate

[huntc]

Thanks again for this crate.

I'm attempting a cross build and note that the ratchet-deflate package specifically enables zlib as a feature flag on flate2.

Is there a specific reason for enabling the zlib flag, thus requiring C compilation? Would you consider a PR to feature-flag enabling ratchet-deflate to accept flate2's rust_backend feature in addition to a zlib feature that could be the default?

[huntc]

It turns out that zlib is actually a requirement given the use of window bits. Closing.

[huntc]

Reopening if I may. It appears that there is support for zlib-rs via its C API (rust-lang/flate2-rs#400). Thus we should be able to support the zlib-rs feature flag with this crate. Do you see an issue with that? Window bits are supported… Thanks.