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/oat_file.cc b/runtime/oat_file.cc
index 46a4d53..74dfe91 100644
--- a/runtime/oat_file.cc
+++ b/runtime/oat_file.cc
@@ -42,7 +42,7 @@
                              std::string* error_msg) {
   CHECK(!oat_contents.empty()) << location;
   CheckLocation(location);
-  UniquePtr<OatFile> oat_file(new OatFile(location));
+  std::unique_ptr<OatFile> oat_file(new OatFile(location));
   oat_file->begin_ = &oat_contents[0];
   oat_file->end_ = &oat_contents[oat_contents.size()];
   return oat_file->Setup(error_msg) ? oat_file.release() : nullptr;
@@ -71,7 +71,7 @@
   //
   // On host, dlopen is expected to fail when cross compiling, so fall back to OpenElfFile.
   // This won't work for portable runtime execution because it doesn't process relocations.
-  UniquePtr<File> file(OS::OpenFileForReading(filename.c_str()));
+  std::unique_ptr<File> file(OS::OpenFileForReading(filename.c_str()));
   if (file.get() == NULL) {
     *error_msg = StringPrintf("Failed to open oat filename for reading: %s", strerror(errno));
     return NULL;
@@ -88,7 +88,7 @@
                              const std::string& location,
                              byte* requested_base,
                              std::string* error_msg) {
-  UniquePtr<OatFile> oat_file(new OatFile(location));
+  std::unique_ptr<OatFile> oat_file(new OatFile(location));
   bool success = oat_file->Dlopen(elf_filename, requested_base, error_msg);
   if (!success) {
     return nullptr;
@@ -102,7 +102,7 @@
                               bool writable,
                               bool executable,
                               std::string* error_msg) {
-  UniquePtr<OatFile> oat_file(new OatFile(location));
+  std::unique_ptr<OatFile> oat_file(new OatFile(location));
   bool success = oat_file->ElfFileOpen(file, requested_base, writable, executable, error_msg);
   if (!success) {
     CHECK(!error_msg->empty());