Fix crash on shutdown when update in progress.

The ActionProcessor destructor normally calls the ProcessingStop method
on the delegate. For the UpdateAttempter this call re-schedules a new
update attempt on a half-destroyed update_attempter instance, crashing
update_engine on SIGTERM when the ActionProcessor was running.

This patch inhibits the ActionProcessor from notifying the delegate of
the processor stopping when destroying the update_attempter instance.
It also fixes the declaration order of the dbus_adaptor_ and disables
its usage during daemon shutdown.

Bug: 24989397
TEST=start update-engine; (update_engine_client --update &); sleep 6; stop update-engine; tail /var/log/update_engine.log
TEST=FEATURES=test emerge-link update_engine

Change-Id: I0a40067f63e89759ff80c79cecb6f89b10dba0c2
diff --git a/common/action_processor.cc b/common/action_processor.cc
index c5270a4..7ccdfbd 100644
--- a/common/action_processor.cc
+++ b/common/action_processor.cc
@@ -30,13 +30,10 @@
     : current_action_(nullptr), delegate_(nullptr) {}
 
 ActionProcessor::~ActionProcessor() {
-  if (IsRunning()) {
+  if (IsRunning())
     StopProcessing();
-  }
-  for (std::deque<AbstractAction*>::iterator it = actions_.begin();
-       it != actions_.end(); ++it) {
-    (*it)->SetProcessor(nullptr);
-  }
+  for (auto action : actions_)
+    action->SetProcessor(nullptr);
 }
 
 void ActionProcessor::EnqueueAction(AbstractAction* action) {