Change UniquePtr to std::unique_ptr

UniquePtr.h in libnativehelper/include is deprecated and will be removed
soon. Switching to the standard std::unique_ptr.

(cherry picked from commit 4e7d18a72f72967a881bcdf78167011a836538ef)

Bug: 63686260
Test: builds, cmd works in the device.
Merged-In: Ib008acd1dd7dba2305b0797c9dc7bab1aa747e7d
Change-Id: Ib008acd1dd7dba2305b0797c9dc7bab1aa747e7d
diff --git a/cmds/cmd/cmd.cpp b/cmds/cmd/cmd.cpp
index 7e05d72..014c995 100644
--- a/cmds/cmd/cmd.cpp
+++ b/cmds/cmd/cmd.cpp
@@ -35,12 +35,11 @@
 #include <fcntl.h>
 #include <sys/time.h>
 #include <errno.h>
+#include <memory>
 
 #include "selinux/selinux.h"
 #include "selinux/android.h"
 
-#include <UniquePtr.h>
-
 #define DEBUG 0
 
 using namespace android;
@@ -55,7 +54,7 @@
         freecon(p);
     }
 };
-typedef UniquePtr<char[], SecurityContext_Delete> Unique_SecurityContext;
+typedef std::unique_ptr<char[], SecurityContext_Delete> Unique_SecurityContext;
 
 class MyShellCallback : public BnShellCallback
 {