cpu: Initialize the O3 pipeline from startup()

The entire O3 pipeline used to be initialized from init(), which is
called before initState() or unserialize(). This causes the pipeline
to be initialized from an incorrect thread context. This doesn't
currently lead to correctness problems as instructions fetched from
the incorrect start PC will be squashed a few cycles after
initialization.

This patch will affect the regressions since the O3 CPU now issues its
first instruction fetch to the correct PC instead of 0x0.

src/cpu/o3/commit_impl.hh

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2011 ARM Limited
+ * Copyright (c) 2010-2012 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -348,7 +348,7 @@ DefaultCommit<Impl>::setROB(ROB *rob_ptr)
 
 template <class Impl>
 void
-DefaultCommit<Impl>::initStage()
+DefaultCommit<Impl>::startupStage()
 {
     rob->setActiveThreads(activeThreads);
     rob->resetEntries();