evdev-proto is installed by a dependency, so some files have been missed:
In file included from ../sway/input/cursor.c:3:
/usr/local/include/libevdev-1.0/libevdev/libevdev.h:30:10: fatal error: 'linux/input.h' file not found
#include <linux/input.h>
^~~~~~~~~~~~~~~
../swaybar/i3bar.c:3:10: fatal error: 'linux/input-event-codes.h' file not found
#include <linux/input-event-codes.h>
^~~~~~~~~~~~~~~~~~~~~~~~~~~