(1) Update both static and shared lib to export libhwui headers
(2) Work around problem in current make system where a static
libraries dependencies are not transitively included by moving
those dependencies into a file that can be included by targets
using libhwui_static.
(3) Do not expose protobuf headers to clients outside of HWUI
Change-Id: I08470c02a83ae64116081eff0c2050878990c6ed
