trace: Add more COM debugging.
trace: Add more COM debugging.

To try to diagnose regression introduced by ealier commits, whereby
map_buffer randomly fail, but only on special circunstances.

trtt/apitrace,schulmar/apitrace,schulmar/apitrace,schulmar/apitrace,schulmar/apitrace,trtt/apitrace,apitrace/apitrace,apitrace/apitrace,trtt/apitrace,schulmar/apitrace,trtt/apitrace,apitrace/apitrace,apitrace/apitrace,trtt/apitrace