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/class_linker_test.cc b/runtime/class_linker_test.cc
index 0db08aa..9970dd5 100644
--- a/runtime/class_linker_test.cc
+++ b/runtime/class_linker_test.cc
@@ -18,7 +18,7 @@
 
 #include <string>
 
-#include "UniquePtr.h"
+#include "UniquePtrCompat.h"
 #include "class_linker-inl.h"
 #include "common_runtime_test.h"
 #include "dex_file.h"