net-snmp: General fixup

- Remove unused inputs (unzip, ncurses)
- Make some buildInputs native
- Fix website
- Wrap the needed perl libraries using `withPackages`
- Make Perl support optional and disable it by default because it didn't
  work previously because net-snmp is built without its perl modules
  (the SNMP module to be specific) which the perl tools need

pkgs/servers/monitoring/net-snmp/default.nix

@@ -1,7 +1,14 @@
 { lib, stdenv, fetchurl, fetchpatch, autoreconfHook, removeReferencesTo
-, file, openssl, perl, perlPackages, unzip, nettools, ncurses }:
+, file, openssl, perl, perlPackages, nettools, gnused
+, withPerlTools ? false }: let
 
-stdenv.mkDerivation rec {
+  perlWithPkgs = perl.withPackages (ps: with ps; [
+    JSON
+    TermReadKey
+    Tk
+  ]);
+
+in stdenv.mkDerivation rec {
   pname = "net-snmp";
   version = "5.9.1";
 
@@ -37,8 +44,9 @@ stdenv.mkDerivation rec {
     substituteInPlace testing/fulltests/support/simple_TESTCONF.sh --replace "/bin/netstat" "${nettools}/bin/netstat"
   '';
 
-  nativeBuildInputs = [ autoreconfHook nettools removeReferencesTo unzip ];
-  buildInputs = with perlPackages; [ file perl openssl ncurses JSON Tk TermReadKey ];
+  nativeBuildInputs = [ autoreconfHook nettools removeReferencesTo gnused file ];
+  buildInputs = [ openssl ]
+    ++ lib.optional withPerlTools perlWithPkgs;
 
   enableParallelBuilding = true;
   doCheck = false;  # tries to use networking
@@ -56,7 +64,7 @@ stdenv.mkDerivation rec {
 
   meta = with lib; {
     description = "Clients and server for the SNMP network monitoring protocol";
-    homepage = "http://net-snmp.sourceforge.net/";
+    homepage = "http://www.net-snmp.org/";
     license = licenses.bsd3;
     platforms = platforms.linux;
   };