libevdev/libmtdev cannot be used unless evdev-proto is installed. requiring evdev-proto upstream projects that use libevdev/libmtdev no longer need to check for FreeBSD-specific package.
$ fgrep -r linux/input.h /usr/local/include /usr/local/include/libevdev-1.0/libevdev/libevdev.h:#include <linux/input.h> /usr/local/include/libevdev-1.0/libevdev/libevdev.h: * linux/input.h shipped with libevdev. /usr/local/include/libevdev-1.0/libevdev/libevdev.h: * @include linux/input.h /usr/local/include/libevdev-1.0/libevdev/libevdev.h: * meaning, matching the axis names in linux/input.h. Some devices merely /usr/local/include/mtdev.h:#include <linux/input.h>