Add the rpcsvc-proto package to the libc port inputs

The libc "port" requires the rpcgen utility to generate some source
files. This was previously provided by glibc, but is missing in the
current version. The output of libc port remains constant.

packages/genodelabs/ports.nix

@@ -32,7 +32,7 @@ with pkgs;
   jpeg.hash = "sha256-RLVnlrnYGrhqr3Feikoi/BNditCaKN0u3t9/UDpl2wQ=";
   libc = {
     hash = "sha256-BSZcO25jbH8+OkJWGyJxxVYuQ4Y3yDt0DNsYcITwqxA=";
-    nativeBuildInputs = [ gcc ];
+    nativeBuildInputs = [ gcc rpcsvc-proto ];
   };
   libiconv.hash = "sha256-25YcW5zo1fE33ZolGQroR+KZO8wHEdN1QXa7+MhwS78=";
   libpng.hash = "sha256-hNmSWN4gEk4UIjzkGD4j5qFooMCVXLwcBeOeFumvh+4=";