* miscfuncs.h (NT_readline::close): New function to close handle.

(NT_readline::~NT_readline): Call close.
	* sec_auth.cc (verify_token): Use constructor to initialize tok_usersid.
	* security.h (cygsid::cygsid): Add copy constructor taking cygsid as
	source.

winsup/cygwin/miscfuncs.h

@@ -38,7 +38,8 @@ public:
   NT_readline () : fh (NULL) {}
   bool init (POBJECT_ATTRIBUTES attr, char *buf, ULONG buflen);
   PCHAR gets ();
-  ~NT_readline () { if (fh) NtClose (fh); }
+  void close () { if (fh) NtClose (fh); fh = NULL; }
+  ~NT_readline () { close (); }
 };
 
 extern "C" void yield ();