lldpd: fix build

The build missed `openssl` as input and failed with an error like this:

```
/nix/store/7n1h80xkbjhcijzp0iylk0nc7w05vy8k-net-snmp-5.8/include/net-snmp/library/scapi.h:14:10: fatal error: openssl/ossl_typ.h: No such file or directory
#include <openssl/ossl_typ.h> /* EVP_MD */
^~~~~~~~~~~~~~~~~~~~
compilation terminated.
```

This also unbreaks `osquery` (https://hydra.nixos.org/build/88547811).

See also https://hydra.nixos.org/build/88562937

pkgs/tools/networking/lldpd/default.nix

···
 { stdenv, lib, fetchurl, pkgconfig, removeReferencesTo
-, libevent, readline, net_snmp }:
+, libevent, readline, net_snmp, openssl
+}:
 
 stdenv.mkDerivation rec {
   name = "lldpd-${version}";
···
   ];
 
   nativeBuildInputs = [ pkgconfig removeReferencesTo ];
-  buildInputs = [ libevent readline net_snmp ];
+  buildInputs = [ libevent readline net_snmp openssl ];
 
   enableParallelBuilding = true;