Compatibility layer to transition from UniquePtr to std::unique_ptr.

Use ART_WITH_STLPORT (enabled for the target) to cause the use of UniquePtr,
for the host switch to std::unique_ptr. For now the type remains called
UniquePtr.
Make dalvik compile with clang on the host, move its build to C++11.

Change-Id: I5ba8d2757904bc089ed62047ea03de3c0853fb12
diff --git a/test/ReferenceMap/stack_walk_refmap_jni.cc b/test/ReferenceMap/stack_walk_refmap_jni.cc
index 180db4c..d8a0eef 100644
--- a/test/ReferenceMap/stack_walk_refmap_jni.cc
+++ b/test/ReferenceMap/stack_walk_refmap_jni.cc
@@ -16,7 +16,7 @@
 
 #include <stdio.h>
 
-#include "UniquePtr.h"
+#include "UniquePtrCompat.h"
 #include "class_linker.h"
 #include "dex_file-inl.h"
 #include "gc_map.h"