Low-level bindings to the librecast C library

Building librecast-sys

Steps we take

1. pkg-config is used to find the librecast library on the current system.
2. ./configure and make are tried next with the librecast source in ./vendor/librecast.

Build Requirements

You will need a C compiler and pkg-config installed, like you would normally for an autotools project.

Development

It's nice to run these when developing:

cargo fmt
cargo build --verbose
cargo test --verbose
cargo clippy -- -D warnings -A clippy::missing_safety_doc
cargo doc --no-deps --verbose

but there will be some using Forgejo Actions soon.