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/compiler/dex/frontend.h b/compiler/dex/frontend.h
index f714ecd..c3b8d12 100644
--- a/compiler/dex/frontend.h
+++ b/compiler/dex/frontend.h
@@ -101,10 +101,10 @@
     }
 
   private:
-    UniquePtr< ::llvm::LLVMContext> llvm_context_;
+    std::unique_ptr< ::llvm::LLVMContext> llvm_context_;
     ::llvm::Module* llvm_module_;  // Managed by context_.
-    UniquePtr<art::llvm::IntrinsicHelper> intrinsic_helper_;
-    UniquePtr<art::llvm::IRBuilder> ir_builder_;
+    std::unique_ptr<art::llvm::IntrinsicHelper> intrinsic_helper_;
+    std::unique_ptr<art::llvm::IRBuilder> ir_builder_;
 };
 
 class CompiledMethod;