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/runtime/mirror/object_test.cc b/runtime/mirror/object_test.cc
index 537fe85..e0fd6a2 100644
--- a/runtime/mirror/object_test.cc
+++ b/runtime/mirror/object_test.cc
@@ -36,7 +36,7 @@
 #include "object_array-inl.h"
 #include "handle_scope-inl.h"
 #include "string-inl.h"
-#include "UniquePtr.h"
+#include "UniquePtrCompat.h"
 
 namespace art {
 namespace mirror {