`bssl-sys` is generated by building `boringssl` with `-DRUST_BINDINGS=<target>`.
You are intended to inject the resulting package into your build, either by path
if you depend on it directly, or via `.cargo/config` if you depend indirectly
through `openssl` or a similar package.
This placeholder package is here to prevent others from populating this crate on
crates.io and tricking users who have not configured their build properly into
downloading it.