libutils: Fix missing definition of shared_ptr and unique_ptr

This includes memory header for shared_ptr and unique_ptr templates.
Fixes the following errors:

RefBase.h:803:1: error: ‘shared_ptr’ does not name a type
RefBase.h:810:1: error: ‘unique_ptr’ does not name a type

Change-Id: I6a7a67333c9ef05250c5a3c6199d7fac288f946b
diff --git a/libutils/include/utils/RefBase.h b/libutils/include/utils/RefBase.h
index f3acd6f..5e3fa7d 100644
--- a/libutils/include/utils/RefBase.h
+++ b/libutils/include/utils/RefBase.h
@@ -210,6 +210,7 @@
 
 #include <atomic>
 #include <functional>
+#include <memory>
 #include <type_traits>  // for common_type.
 
 #include <stdint.h>