Fix checker bug.

src/cpu/checker/thread_context.hh:
    Checker's TC should only copy state, and not fully take over from the old context (prevents it from accidentally stealing the quiesce event).

--HG--
extra : convert_revision : 5760f9c5bae749f8d1df35e4c898df13e41b0224

src/cpu/checker/thread_context.hh

@@ -133,7 +133,7 @@ class CheckerThreadContext : public ThreadContext
     void takeOverFrom(ThreadContext *oldContext)
     {
         actualTC->takeOverFrom(oldContext);
-        checkerTC->takeOverFrom(oldContext);
+        checkerTC->copyState(oldContext);
     }
 
     void regStats(const std::string &name) { actualTC->regStats(name); }