* cygerrno.h (__set_errno): Modify debugging output to make searching strace

* cygerrno.h (__set_errno): Modify debugging output to make searching strace
logs easier.  Throughout, change /dev/tty* to /dev/pty*.  Throughout, add flags
argument to fhandler_*::dup methods.
* devices.in: Rename (temporarily?) /dev/ttyN to /dev/ptyN.  Add /dev/ptymN
devices for pty masters.
* devices.cc: Regenerate.
* devices.h (MAX_CONSOLES): Set to max number supported by devices.in.
(fh_devices::FH_PTMX): Rename from FH_PTYM.
(device::operator int): Return by reference.
* dtable.cc (fh_alloc): Take pc as an argument rather than just the device.
This makes debugging easier since more information is available.  Actually
implement handling for already-allocated pty master devices.  Make different
decisions when generating fhandler for not-opened devices.  Add kludge to deal
with opening /dev/tty.
(cnew_no_ctor): New macro.
(build_fh_pc): Make debugging output more verbose.  Use new clone() fhandler
interface to duplicate archetypes.  Reset last term opened.
(dtable::dup_worker): Use Use new clone() fhandler interface to duplicate
archetypes.  Pass flags to child dup handler.
(dtable::dup3): Set O_NOCTTY flag if newfd is not stdin/stdout/stderr.
* fhandler.cc (fhandler_base::reset): Rename from operator =() and reduce
functionality and sense of copy direction.
(fhandler_base::open_with_arch): Use published interface to query io_handle().
Use new copyto() fhandler method to copy from/to found archetype.
* fhandler.h: Throughout, delete size(), add copyout, clone, and fhandler_*
(void *) methods.
(fhandler_base::reset): Rename from operator =().
(fhandler_termios::is_dev_tty): Delete.
(fhandler_termios): change "protected" region to "private".
(fhandler_termios::is_dev_tty): Delete.
(fhandler_termios): Rearrange protected/public.
(fhandler_termios::fhandler_termios): Remember last fhandler_termios "opened".
(fhandler_termios::~fhandler_termios): Forget last fhandler_termios opened.
(ioctl): Rename from ioctl_termios.  Take a void * argument.  Reflect argument
change in pinfo::set_ctty.
(fhandler_console::dup): Declare new function.  Set ctty here if appropriate.
(fhandler_pty_master::from_master): Privatize.
(fhandler_pty_master::to_master): Ditto.
(fhandler_pty_master::dwProcessId): Ditto.
(fhandler_pty_master::fhandler_pty_master): Add an `int' argument.
(fhandler_pty_master::open_setup): Declare new function.
(fhandler_pty_master::~fhandler_pty_master): Declare new method.
(fhandler_nodevice): Remove commented out function declaration.
* fhandler_console.cc: Use get_ttyp() instead of tc() throughout.
(fhandler_console::dup): Define new function to set controlling ctty on dup, as
appropriate.
(fhandler_console::ioctl): Reflect ioctl_termios name change.
(fhandler_console::setup): Rename from get_tty_stuff.
(fhandler_console::open_setup): Reflect argument change in pinfo::set_ctty.
(fhandler_console::fhandler_console): Set _tc here.
* fhandler_termios.cc (handler_termios::ioctl): Rename.  Take a void * arg like
other ioctl functions.
* fhandler_tty.cc (fhandler_pty_slave::dup): Call myself->set_ctty to
potentially reset the controlling terminal.
(fhandler_pty_slave::ioctl): Reflect name/arg change for ioctl_termios.
(fhandler_pty_slave::fhandler_pty_slave): Take a "unit" argument.  Call setup()
here so that we will know the unit number of this fhandler as soon as possible.
Set the unit as appropriate.
(handler_pty_master::open): Move most stuff to constructor and open_setup.
(handler_pty_slave::open_setup): Reflect argument change in pinfo::set_ctty.
(handler_pty_master::open_setup): Define new function.
(fhandler_pty_master::cleanup): Clear handles as a flag that the destructor
does not have to do "close" operations.
(fhandler_pty_master::close): Ditto.
(fhandler_pty_master::~fhandler_pty_master): Define new method.
(fhandler_pty_master::ioctl): Reflect name/arg change for ioctl_termios.
(fhandler_pty_master::setup): Allocate tty here.  Rely on handles being
returned from allocated test rather than opening them here.  Avoid setting
_need_nl here since it is already zeroed in the constructor.  Set up device
information with DEV_TTYM_MAJOR.
* path.h (path_conv &operator =): Take a const argument.
(path_conv::dup): Ditto.
(pathconv_arg::PC_OPEN): New enum.
(pathconv_arg::PC_CTTY): Ditto.
(path_types::PATH_CTTY): Ditto.
(path_types::PATH_OPEN): Ditto.
(path_conv::isopen): New method.
(path_conv::isctty_capable): Ditto.
* path.cc (path_conv::check): Set PATH_OPEN and PATH_CTTY as appropriate.
* pipe.cc (fhandler_pipe::open): Use copyto to copy pipe handle.
* syscall.cc (open): Reinstate fd > 2 check to disallow resetting ctty on
non-std* handles.
* tty.cc (tty_list::allocate): Pass out handles for allocated tty.  use
`not_allocated' to find unallocated ttys.  Avoid keeping the lock since the
allocation of the tty should be sufficient to prevent multiple access.
(tty::not_allocated): Clarify comment.  Rename.  Return handles when an unused
tty is found.  Simply test for existing tty.
(tty::exists): Rewrite to use `not_allocated'.
* tty.h (NTTYS): Reset down to actual number supported by devices.in.
(tty::not_allocated): Declare new function.
(tty_list::allocate): Pass out read/write tty handles.  Zero them when not
found.
* fhandler_proc.cc: Reflect name change from FH_PTYM -> FH_PTMX.
* pinfo.h (pinfo::set_ctty): Reduce/reorder arguments passed in.
* pinfo.cc (pinfo::set_ctty): Ditto.  Just use tc() built into the passed-in
fhandler_termios pointer.  Return true if ctty is assigned.
* syscalls.cc (open): Call build_fh_pc with PC_OPEN flag.  Set PC_CTTY if
appropriate.
(stat_worker): Remove is_dev_tty () stuff.