Investigating the test failures in MR!1823, it turns out
that sometimes in Win7, at process exit, not all the dll unload
debug events are sent (in traces, only the last loaded dll gets the
event).
I don't know what it only shows now :-(, but that seems very
replicable (it happens every time with new job to TestBot).

So mark the case of missing unload dll debug event as broken
(still checking that the load dll debug event has been received).
Signed-off-by: Eric Pouech <eric.pouech@gmail.com>