Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.Approved by: re (implicit)Sponsored by: The FreeBSD Foundation
Moved mcgrab(1) into a separate directory -- our .mk infrastructuredoesn't currently have support for building multiple programs in asingle makefile.While here, fixed manpages and makefiles (missing dependencies).
Add a new program to the multicast test suite. The mcgrab programis used to grab and hold some number of multicast addresses in orderto test what happens when an interface goes over the number of multicastaddresses it can filter in hardware.
Add a manual page and a Makefile.Add code to reflect packets back from the sink so that we can measureround trip at the source.