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/jni_internal_test.cc b/runtime/jni_internal_test.cc
index 83e9b10..3429827 100644
--- a/runtime/jni_internal_test.cc
+++ b/runtime/jni_internal_test.cc
@@ -539,8 +539,8 @@
   ExpectException(aioobe_); \
   \
   /* Prepare a couple of buffers. */ \
-  UniquePtr<scalar_type[]> src_buf(new scalar_type[size]); \
-  UniquePtr<scalar_type[]> dst_buf(new scalar_type[size]); \
+  std::unique_ptr<scalar_type[]> src_buf(new scalar_type[size]); \
+  std::unique_ptr<scalar_type[]> dst_buf(new scalar_type[size]); \
   for (jsize i = 0; i < size; ++i) { src_buf[i] = scalar_type(i); } \
   for (jsize i = 0; i < size; ++i) { dst_buf[i] = scalar_type(-1); } \
   \