end of life sysutils/zap

[Ian Darwin]

The sysutils/zap port which I nominally maintain has been obsoleted by 
pkill which is in the base system. I therefore propose to remove this port.

Should I leave behind (for a while) a minimal Makefile with s/t like
BROKEN=   "obsoleted by pkill(1), in base system"

Or is it better just to get rid of it altogether?