nrg: update master_sites, disable livecheck

A homepage for this port no longer exists on the internet, not even
on archive.org. The source is now only available from MacPorts distfile
mirrors AFAICT. A currently maintained project that might make a good substitute
in terms of a graphical front end to rrdtool is cacti.

net/nrg/Portfile

@@ -19,8 +19,7 @@ long_description    NRG is an RRDtool front-end tool to monitor traffic and load
 
 # website no longer exists
 homepage            http://ginseng.hep.wisc.edu/NRG/
-master_sites        ftp://noc.hep.wisc.edu/src/nrg/ \
-                    ftp://noc.hep.wisc.edu/pub/src/nrg/
+master_sites        macports_distfiles:${name}
 
 checksums           rmd160  1192ce02d14447abdcff994671693eeb4ca67e28 \
                     sha256  ef851705f9ebd2bf55892823f258c7cffc079ae0276df4f40860c520262971c2
@@ -107,6 +106,8 @@ post-destroot {
         ${destroot}${prefix}/var/${name}/Site.mconf.sample
 }
 
+livecheck.type      none
+
 notes \
 "#### To complete the NRG installation ####