collectd: more plugins, update to 5.11.0

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

I just pushed a bunch of commits that re-work collectd's library handling, 
add more plugins (ceph gmond gps grpc log_logstash multimeter notify_desktop 
nut openldap pinba sysevent ted tokyotyrant varnish write_kafka write_mongodb 
virt xen xmms), and update to 5.11.0 (which includes a NetBSD implementation 
of the NFS plugin I wrote and a correction to the NetBSD implementation of 
the disk plugin).

On a side note, I also currently try to upstream all of he@'s NetBSD plugin
implementations now included as pkgsrc patches.