* dcrt0.cc (dll_crt0_0): Call tty_list::init_session here.

(dll_crt0_1): Reflect renaming from tty_init to tty::init_session.
(do_exit): Reflect moving of tty_terminate into tty_list.
* exceptions.cc (events_init): Move tty_mutex stuff elsewhere.
* fhandler_console.cc (set_console_title): Use lock_ttys class.
* fhandler_termios.cc (fhandler_termios::bg_check): Make debug output more
accurate.
* fhandler_tty.cc (fhandler_tty_slave::open): Reflect move of attach_tty into
tty_list class.  Don't attempt to grab master end of pty if master doesn't
exist.
(fhandler_pty_master::open): Reflect move of allocate_tty into tty_list class.
Use lock_ttys::release to release mutex.  Improve debugging output.
(fhandler_pty_master::setup): Remove if 0'ed block.  Fix argument to
SetNamedPipeHandleState.
* pinfo.cc (_pinfo::set_ctty): Lock ttys before setting sid/pgid.  Improve
debugging.  Add temporary debugging.
* tty.cc (tty_list::init_session): New function.
(tty::init_session): Rename from tty_init.  Reflect move of attach_tty to
tty_list class.
(tty::create_master): Rename from create_tty_master.
(tty_list::attach): Rename from attach_tty.  Reflect renaming of connect_tty to
connect.  Ditto for allocate_tty.
(tty_terminate): Delete.
(tty_list::terminate): Subsume tty_terminate.  Use lock_ttys rather than
manipulating mutex directly.
(tty_list::allocate): Rename from allocate_tty.  Use lock_ttys rather than
manipulating mutex directly.  Don't set sid here since linux apparently doesn't
do this.  Reflect move of create_tty_master into tty.
(lock_ttys::lock_ttys): Define new constructor.
(lock_ttys::release): New function.
* tty.h (tty::exists): Return false immediately if !master_pid.
(tty::set_master_closed): Define new function.
(tty::create_master): Ditto.
(tty::init_session): Ditto.
(tty_list::mutex): New field.
(tty_list::allocate): Define new function.
(tty_list::connect): Ditto.
(tty_list::attach): Ditto.
(tty_list::init_session): Ditto.
(lock_ttys): New class.
(tty_init): Delete declaration.
(tty_terminate): Ditto.
(attach_tty): Ditto.
(create_tty_master): Ditto.

winsup/cygwin/dcrt0.cc

@@ -768,6 +768,7 @@ dll_crt0_0 ()
 
   /* Initialize events */
   events_init ();
+  tty_list::init_session ();
 
   cygheap->cwd.init ();
 
@@ -867,9 +868,8 @@ dll_crt0_1 (void *)
   if (!threadfunc_ix)
     system_printf ("internal error: couldn't determine location of thread function on stack.  Expect signal problems.");
 
-
   /* Connect to tty. */
-  tty_init ();
+  tty::init_session ();
 
   if (!__argc)
     {
@@ -1110,7 +1110,7 @@ do_exit (int status)
   if (exit_state < ES_TTY_TERMINATE)
     {
       exit_state = ES_TTY_TERMINATE;
-      tty_terminate ();
+      cygwin_shared->tty.terminate ();
     }
 
   myself.exit (n);