Clean up databases/rrdtool
Change library dependensies to use USES= where applicable.
Build ports documentation and examples, depending on respective option.
Add two new options, NLS and GRAPH, the GRAPH option enables the rrdtool graph
command, which pulls in cario and a lot of other dependencies. 
Add missing dependencies.
Becase of shlib version bump, bump portrevision on depending ports.
PR: 192024  (based on)
Submitted by: asomers
Approved by: portmgr (blanket, portrevision bumps)