binder: Move public headers to a separate folder

Move the |binder_constants| header file which is needed by clients
to a separate include directory.

BUG: 29879355
Change-Id: Ic6b192d39d1d0da9e2f48c70c1f78eb318f2872d
Signed-off-by: Roshan Pius <rpius@google.com>
4 files changed