AAPT2: Define intermediate compiled XML proto

This proto format is meant to encapsulate more information
that is specific to Android and allows for easier validation
and manipulation across tools.

Test: make aapt2_tests
Change-Id: I13bc34a460671fc0a36246be0d287a3d37d244d6
diff --git a/tools/aapt2/Android.bp b/tools/aapt2/Android.bp
index 15fb016..24aa6eb 100644
--- a/tools/aapt2/Android.bp
+++ b/tools/aapt2/Android.bp
@@ -143,7 +143,8 @@
         "xml/XmlDom.cpp",
         "xml/XmlPullParser.cpp",
         "xml/XmlUtil.cpp",
-        "Format.proto",
+        "Resources.proto",
+        "ResourcesInternal.proto",
     ],
     proto: {
         export_proto_headers: true,