Merge "Include <functional> for std::function and std::placeholders" into main am: e5896f0f

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2674342



Change-Id: I3bff9b1908b006069248ebc3e9f9ad7793222e3b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>