Declare our `cfg()`s in Cargo.toml

Starting in Rust 1.80, rustc checks that all cfg values are expected and warns if they are not. This is intended to protect against typos and other mistakes.

Change-Id: I2d6f76536b8c585796e71ef7f65550ef8d312247
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/69867
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

rust/bssl-sys/Cargo.toml

diff --git a/rust/bssl-sys/Cargo.toml b/rust/bssl-sys/Cargo.toml
index 76087e5..7e863da 100644
--- a/rust/bssl-sys/Cargo.toml
+++ b/rust/bssl-sys/Cargo.toml
@@ -9,3 +9,6 @@
 # This exists to workaround a limitation in cargo:
 # https://github.com/rust-lang/cargo/issues/3544
 links = "bssl"
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(unsupported_inline_wrappers)', 'cfg(soong)'] }