Mark gcc unmaintained

Author: jayvdb

crates/gcc/RUSTSEC-0000-0000.md

@@ -0,0 +1,19 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "gcc"
+date = "2025-11-17"
+url = "https://crates.io/crates/gcc"
+informational = "unmaintained"
+
+[versions]
+patched = []
+```
+
+# gcc crate is unmaintained
+
+The `gcc` crate is deprecated and no longer actively maintained. If you rely on this crate, consider switching to a recommended alternative.
+
+## Recommended alternatives
+
+- [`cc`](hhttps://crates.io/crates/cc)