AAPT2: Record public status in a more robust way

This allows us to store the source and comments of a resource's
public declaration and avoids issues where there is no default
configuration for a publicly declared resource (like with drawables
of various densities) and AAPT2 mistakenly took this as an error.

Change-Id: I07a2fe9f551daefcce842f205fb219d2fa453ebc
diff --git a/tools/aapt2/ResourceTable.h b/tools/aapt2/ResourceTable.h
index 3591d11..94bacd8 100644
--- a/tools/aapt2/ResourceTable.h
+++ b/tools/aapt2/ResourceTable.h
@@ -35,6 +35,7 @@
  */
 struct Public {
     bool isPublic = false;
+    SourceLine source;
     std::u16string comment;
 };