* fhandler.h (fhandler_tty_slave::ttyname): Use name from pc since it is

guaranteed to be accurate.
* fhandler_tty.cc (fhandler_tty_slave::open): Increment open_fhs appropriate
when copying ctty.
(fhandler_tty_slave::close): Remove special case handling for exit_state.  Use
ctty < 0 check instead.
(fhandler_tty_common::close): Set io_handle to NULL after closing.
* syscalls.cc (close_all_files): Specifically close cygheap->ctty, if
appropriate.

winsup/cygwin/fhandler.h

@@ -919,6 +919,7 @@ class fhandler_tty_slave: public fhandler_tty_common
   select_record *select_read (select_record *s);
   int cygserver_attach_tty (HANDLE*, HANDLE*);
   int get_unit () __attribute__ ((regparm (1)));
+  virtual char const *ttyname () { return pc.dev.name; }
 };
 
 class fhandler_pty_master: public fhandler_tty_common