Now we have a proper C++ library, use std::unique_ptr.

Also remove the Android.libcxx.mk and other bits of stlport compatibility
mechanics.

Change-Id: Icdf7188ba3c79cdf5617672c1cfd0a68ae596a61
diff --git a/runtime/gc/accounting/remembered_set.cc b/runtime/gc/accounting/remembered_set.cc
index 1def334..3ff5874 100644
--- a/runtime/gc/accounting/remembered_set.cc
+++ b/runtime/gc/accounting/remembered_set.cc
@@ -16,6 +16,8 @@
 
 #include "remembered_set.h"
 
+#include <memory>
+
 #include "base/stl_util.h"
 #include "card_table-inl.h"
 #include "heap_bitmap.h"
@@ -30,7 +32,6 @@
 #include "mirror/object_array-inl.h"
 #include "space_bitmap-inl.h"
 #include "thread.h"
-#include "UniquePtrCompat.h"
 
 namespace art {
 namespace gc {