Make cargo all-features build --all --all-targets pass #215
Description
Currently, trying to compile this crate without default features (and probably also some other more obscure feature combinations) does not work. See #213 (in this PR it looks at first like mostly the benchmarks need to be fixed, but actually there's also issues in the production code, mostly related to bindings being cfg'd differently than the code that tries to use them). It'd be cool to get this fixed, as it's currently blocking our CI submodule updates.