Host header files framework used to talk to wayland.

There are 2 header files used by inputflinger and surfaceflinger
respectively to add custom interface between them and wayland. Host them
in wayland-protocols so that they can be referenced by both framework
and wayland code under vendor/google_arc/libs.

This is needed as we can then land wayland code in master branch.

Test: wayland_service builds using these headers.

Change-Id: I15be9e7852f949df4f04184446718ddc52a4d5c5