Fix generation of event labels for getevent.

The recent uapi header update moved all the interesting constants
out into another file. Track that, and add the missing makefile
dependency.

Bug: http://b/27073568

(cherry picked from commit bd02a47b227430e7e9702dcfb11d4eb445847817)

Change-Id: I9323a995511b12905949cba22c59cc28623068f3
2 files changed