Begin migration of art::Atomic to std::atomic.

Change-Id: I4858d9cbed95e5ca560956b9dabd976cebe68333
diff --git a/runtime/base/mutex.h b/runtime/base/mutex.h
index 3f35670..e13c8d5 100644
--- a/runtime/base/mutex.h
+++ b/runtime/base/mutex.h
@@ -160,12 +160,12 @@
     void AddToWaitTime(uint64_t value);
     ContentionLogData() : wait_time(0) {}
   };
-  ContentionLogData contetion_log_data_[kContentionLogDataSize];
+  ContentionLogData contention_log_data_[kContentionLogDataSize];
 
  public:
   bool HasEverContended() const {
     if (kLogLockContentions) {
-      return contetion_log_data_->contention_count > 0;
+      return contention_log_data_->contention_count.LoadSequentiallyConsistent() > 0;
     }
     return false;
   }