net/rtg updates got reverted

[Andrew]

A bunch of fixes to rtg, most importantly making it work with modern 
perl, were committed to the ports tree in rev 484406, but immediately 
reverted.  Can we get that patch reopened, since the port is pretty 
broken without it.
I can confirm that building from r484406 works great on FreeBSD 11.2 and 
12.0.

http://svnweb.freebsd.org/changeset/ports/484406

Thanks,
Andrew Fengler
ScaleEngine Inc.