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/parsed_options.cc b/runtime/parsed_options.cc
index 55b6a27..6d53ba1 100644
--- a/runtime/parsed_options.cc
+++ b/runtime/parsed_options.cc
@@ -25,7 +25,7 @@
 namespace art {
 
 ParsedOptions* ParsedOptions::Create(const Runtime::Options& options, bool ignore_unrecognized) {
-  UniquePtr<ParsedOptions> parsed(new ParsedOptions());
+  std::unique_ptr<ParsedOptions> parsed(new ParsedOptions());
   if (parsed->Parse(options, ignore_unrecognized)) {
     return parsed.release();
   }