Export wayland-client-protocol.h.

This is needed by libwayland_service.

Test: libwayland_service can see wayland-client-protocol.h while
building in master-arc-dev branch.

Change-Id: Icb55e4a8151327e7244b1793c967d14e2ccf98ae
diff --git a/Android.bp b/Android.bp
index a3e9f7b..9c49e28 100644
--- a/Android.bp
+++ b/Android.bp
@@ -88,5 +88,5 @@
     local_include_dirs: ["src"],
     generated_headers: ["wayland_version_header", "wayland_protocol_headers"],
     export_include_dirs: ["src"],
-    export_generated_headers: ["wayland_version_header"],
+    export_generated_headers: ["wayland_version_header", "wayland_protocol_headers"],
 }