Ruby: Delete packet requests during warmup

When warming up caches in Ruby, the CacheRecorder sends fetch requests into
Ruby Sequencers with packet types that require responses. Since responses are
never generated for these CacheRecorder requests, the requests are not deleted
in the packet destructor called from the Ruby hit callback. Free the request.

src/mem/ruby/system/Sequencer.cc

@@ -560,6 +560,8 @@ Sequencer::hitCallback(SequencerRequest* srequest,
     delete srequest;
 
     if (g_system_ptr->m_warmup_enabled) {
+        assert(pkt->req);
+        delete pkt->req;
         delete pkt;
         g_system_ptr->m_cache_recorder->enqueueNextFetchRequest();
     } else if (g_system_ptr->m_cooldown_enabled) {