Use std::unique_ptr instead of UniquePtr.

We're deprecating UniquePtr, so we need to move to the real thing.

Bug: http://b/22403888
Change-Id: I5b7fdf4924dd8c12a8c7dba89278714ca6fdc60a
(cherry picked from commit b0624da1181276ff4caa5e57a7a4abf766902e3e)
diff --git a/cmds/idmap/create.cpp b/cmds/idmap/create.cpp
index 6b2f460..c13d318 100644
--- a/cmds/idmap/create.cpp
+++ b/cmds/idmap/create.cpp
@@ -1,6 +1,6 @@
 #include "idmap.h"
 
-#include <UniquePtr.h>
+#include <memory>
 #include <androidfw/AssetManager.h>
 #include <androidfw/ResourceTypes.h>
 #include <androidfw/ZipFileRO.h>
@@ -15,7 +15,7 @@
 namespace {
     int get_zip_entry_crc(const char *zip_path, const char *entry_name, uint32_t *crc)
     {
-        UniquePtr<ZipFileRO> zip(ZipFileRO::open(zip_path));
+        std::unique_ptr<ZipFileRO> zip(ZipFileRO::open(zip_path));
         if (zip.get() == NULL) {
             return -1;
         }