* cygheap.cc (init_cygheap::close_ctty): Avoid closing console-cttys since they

don't use archetypes and this will just result in double frees.
* dll_init.cc (dll_list::protect): Define.
(dll_list::alloc): Guard list access.
(dll_list::detach): Ditto.
* dll_init.h (dll_list::protect): Declare new muto.
(dll_list::guard): Define/declare function to guard list access.
* fhandler_termios.cc (fhandler_termios::sigflush): Avoid SEGV in pathological
condition of get_ttyp() == NULL.

winsup/cygwin/fhandler_termios.cc

@@ -371,6 +371,9 @@ fhandler_termios::lseek (_off64_t, int)
 void
 fhandler_termios::sigflush ()
 {
-  if (!(get_ttyp ()->ti.c_lflag & NOFLSH))
+  /* FIXME: Checking get_ttyp() for NULL is not right since it should not
+     be NULL while this is alive.  However, we can conceivably close a
+     ctty while exiting and that will zero this. */
+  if (get_ttyp () && !(get_ttyp ()->ti.c_lflag & NOFLSH))
     tcflush (TCIFLUSH);
 }