Requires.private in the pkg-config metadata

[nwalfield]

There's also the Requires.private in the pkg-config metadata, which is currently hardcoded to nettle. I'm about to submit a PR to the Fedora rust-rpm-sequoia package with both this patch, and one to just hard-replace nettle with openssl for their builds... but it'd be cool if there was some easy way to autoconfigure that from build.rs as well.

Originally posted by @ferdnyc in #35 (comment)

[ferdnyc]

Heh. Even split off, this is kind of two things. (Bad habit of mine, sorry.)

[nwalfield]

There's also the Requires.private in the pkg-config metadata, which is currently hardcoded to nettle. I'm about to submit a PR to the Fedora rust-rpm-sequoia package with both this patch, and one to just hard-replace nettle with openssl for their builds... but it'd be cool if there was some easy way to autoconfigure that from build.rs as well.

Good point. I overlooked that. The backend is behind a feature gate (sequoia-openpgp/crypto-nettle, sequoia-openpgp/crypto-openssl, etc.) It would be worth investigating if we could use those to determine how to rewrite that file. Do you want to do that?