collectd: enable a bunch of plugins (by adding more deps)

These are plugins that are internal to collectd; they are bundled in the
source archive. Without this, many of the collectd plugins advertised on
their homepage don't actually work, so I think we should add this.

This change increases the closure size from 129 MiB to 621 MiB. The size
of the collectd store path itself goes from 2 MiB to 2.9 MiB.

Users wanting a smaller closure size can set some (or all) of the
optional inputs to "null" using ".override".

List of new plugins:

  amqp
  apache
  ascent
  bind
  curl
  curl_json
  curl_xml
  dbi
  dns
  iptables
  libvirt
  lvm
  memcachec
  modbus
  mysql
  nginx
  notify_desktop
  pinba
  ping
  postgresql
  redis
  rrdcached
  rrdtool
  sensors
  sigrok
  varnish
  write_http
  write_redis
  write_riemann

pkgs/tools/system/collectd/default.nix

@@ -1,4 +1,29 @@
-{stdenv, fetchurl }:
+{ stdenv, fetchurl
+# optional:
+, pkgconfig ? null  # most of the extra deps need pkgconfig to be found
+, curl ? null
+, iptables ? null
+, libcredis ? null
+, libdbi ? null
+, libgcrypt ? null
+, libmemcached ? null, cyrus_sasl ? null
+, libmodbus ? null
+, libnotify ? null, gdk_pixbuf ? null
+, liboping ? null
+, libpcap ? null
+, libsigrok ? null
+, libvirt ? null
+, libxml2 ? null
+, lm_sensors ? null
+, lvm2 ? null
+, mysql ? null
+, postgresql ? null
+, protobufc ? null
+, rabbitmq-c ? null
+, rrdtool ? null
+, varnish ? null
+, yajl ? null
+}:
 
 stdenv.mkDerivation rec {
   name = "collectd-5.4.1";
@@ -10,6 +35,16 @@ stdenv.mkDerivation rec {
 
   NIX_LDFLAGS = "-lgcc_s"; # for pthread_cancel
 
+  buildInputs = [
+    pkgconfig curl iptables libcredis libdbi libgcrypt libmemcached cyrus_sasl
+    libmodbus libnotify gdk_pixbuf liboping libpcap libsigrok libvirt
+    lm_sensors libxml2 lvm2 mysql postgresql protobufc rabbitmq-c rrdtool
+    varnish yajl
+  ];
+
+  # for some reason libsigrok isn't auto-detected
+  configureFlags = stdenv.lib.optional (libsigrok != null) "--with-libsigrok";
+
   meta = {
     homepage = http://collectd.org;
     description = "collectd is a daemon which collects system performance statistics periodically";