Add some more DISALLOW_COPY_AND_ASSIGN

May help prevent bugs maybe.

Change-Id: Ie73d469dfcd078492ecb3aa28682b42707221202
diff --git a/runtime/linear_alloc.h b/runtime/linear_alloc.h
index 6d8eda6..fcabcc8 100644
--- a/runtime/linear_alloc.h
+++ b/runtime/linear_alloc.h
@@ -42,6 +42,8 @@
  private:
   mutable Mutex lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
   ArenaAllocator allocator_ GUARDED_BY(lock_);
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(LinearAlloc);
 };
 
 }  // namespace art