handle missing rrd_graph support
support HAVE_RRD_GRAPH
Merge pull request #509 from oetiker/support_missing_graph_in_bindings

Support missing graph in bindings
it is rrdtool info not rrdinfo
Merge branch 'master' of github.com:oetiker/rrdtool-1.x
* msync is NOT necessary before munmap, the data gets synced automatically
* remove WILLNEED madvise, this only slows the code down while the os des not seem todo anything sensible with the info