Implement Deref<Target=ByteStr> for CStr

This produces a deref chain of `CStr` -> `BStr` -> `[u8]` which is
present in the Rust-for-Linux analogues of these types.

Link: #134915
Link: Rust-for-Linux/linux#1075
Link: https://lore.kernel.org/all/20250221142816.0c015e9f@eugeo/
Link: Rust-for-Linux/linux#1146

Author: tamird

Diff for: library/core/src/ffi/c_str.rs

@@ -710,6 +710,14 @@ impl AsRef<CStr> for CStr {
     }
 }
 
+impl ops::Deref for CStr {
+    type Target = crate::bstr::ByteStr;
+
+    fn deref(&self) -> &Self::Target {
+        crate::bstr::ByteStr::from_bytes(self.to_bytes())
+    }
+}
+
 /// Calculate the length of a nul-terminated string. Defers to C's `strlen` when possible.
 ///
 /// # Safety