Make addGestureMonitors static

The function is already static, but it's marked as if part of
InputDispatcher. Make it clearly static by moving out of
InputDispatcher.h

Bug: 142017994
Test: none (this is a cherry pick)
Change-Id: I098e86453b7bb8261e08f7fce671db173e2136b0
Merged-In: I098e86453b7bb8261e08f7fce671db173e2136b0
2 files changed