Revert "Change the way tombstones are added to dropbox."

Revert submission 2843682-tombstone-proto

Reason for revert: Android Go build break, b/316637921

Reverted changes: /q/submissionid:2843682-tombstone-proto

Change-Id: Ic9d7b73e97c070fc378becb59799268323d9cead
diff --git a/ProtoLibraries.bp b/ProtoLibraries.bp
index d03bbd2..e7adf20 100644
--- a/ProtoLibraries.bp
+++ b/ProtoLibraries.bp
@@ -34,6 +34,7 @@
         ":ipconnectivity-proto-src",
         ":libstats_atom_enum_protos",
         ":libstats_atom_message_protos",
+        ":libtombstone_proto-src",
         "core/proto/**/*.proto",
         "libs/incident/**/*.proto",
     ],