Expose libtombstone_proto srcs.

Test: treehugger
Change-Id: I4f993e6bf025120bda82eb60f6c534f43030085c
diff --git a/debuggerd/proto/tombstone.proto b/debuggerd/proto/tombstone.proto
index aff50bd..38a06f4 100644
--- a/debuggerd/proto/tombstone.proto
+++ b/debuggerd/proto/tombstone.proto
@@ -1,5 +1,8 @@
 syntax = "proto3";
 
+option java_package = "com.android.server.os";
+option java_outer_classname = "TombstoneProtos";
+
 message Tombstone {
   Architecture arch = 1;
   string build_fingerprint = 2;