defaultCrateOverrides: add rdkafka-sys

pkgs/build-support/rust/default-crate-overrides.nix

@@ -22,6 +22,7 @@
 , clang
 , llvmPackages
 , linux-pam
+, rdkafka
 , ...
 }:
 
@@ -135,6 +136,11 @@ in
     buildInputs = [ postgresql ];
   };
 
+  rdkafka-sys = attr: {
+    nativeBuildInputs = [ pkg-config ];
+    buildInputs = [ rdkafka ];
+  };
+
   rink = attrs: {
     buildInputs = [ gmp ];
     crateBin = [{ name = "rink"; path = "src/bin/rink.rs"; }];