Fix bugs in termios library and cleanup code

This change fixes an issue with the tcflow() magic numbers that was
causing bash to freeze up on Linux. While auditing termios polyfills,
several other issues were identified with XNU/BSD compatibility.

Out of an abundance of caution this change undefines as much surface
area from libc/calls/struct/termios.h as possible, so that autoconf
scripts are less likely to detect non-POSIX teletypewriter APIs that
haven't been polyfilled by Cosmopolitan.

This is a *breaking change* for your static archives in /opt/cosmos if
you use the cosmocc toolchain. That's because this change disables the
ioctl() undiamonding trick for code outside the monorepo, specifically
because it'll lead to brittle ABI breakages like this. If you're using
the cosmocc toolchain, you'll need to rebuild libraries like ncurses,
readline, etc. Yes diamonds cause bloat. To work around that, consider
using tcgetwinsize() instead of ioctl(TIOCGWINSZ) since it'll help you
avoid pulling every single ioctl-related polyfill into the linkage.

The cosmocc script was specifying -DNDEBUG for some reason. It's fixed.

third_party/python/Lib/test/test_ioctl.py

@@ -1,98 +0,0 @@
-import array
-import unittest
-from test.support import import_module, get_attribute
-import os, struct
-
-fcntl = import_module('fcntl')
-termios = import_module('termios')
-get_attribute(termios, 'TIOCGPGRP') #Can't run tests without this feature
-
-if __name__ == 'PYOBJ.COM':
-    import fcntl
-    import termios
-
-try:
-    tty = open("/dev/tty", "rb")
-except OSError:
-    # todo: gh-runners fail on skiptest cosmo issue #431
-    import sys
-    sys.exit()
-    raise unittest.SkipTest("Unable to open /dev/tty")
-else:
-    # Skip if another process is in foreground
-    r = fcntl.ioctl(tty, termios.TIOCGPGRP, "    ")
-    tty.close()
-    rpgrp = struct.unpack("i", r)[0]
-    if rpgrp not in (os.getpgrp(), os.getsid(0)):
-        raise unittest.SkipTest("Neither the process group nor the session "
-                                "are attached to /dev/tty")
-    del tty, r, rpgrp
-
-try:
-    import pty
-except ImportError:
-    pty = None
-
-class IoctlTests(unittest.TestCase):
-    def test_ioctl(self):
-        # If this process has been put into the background, TIOCGPGRP returns
-        # the session ID instead of the process group id.
-        ids = (os.getpgrp(), os.getsid(0))
-        with open("/dev/tty", "rb") as tty:
-            r = fcntl.ioctl(tty, termios.TIOCGPGRP, "    ")
-            rpgrp = struct.unpack("i", r)[0]
-            self.assertIn(rpgrp, ids)
-
-    def _check_ioctl_mutate_len(self, nbytes=None):
-        buf = array.array('i')
-        intsize = buf.itemsize
-        ids = (os.getpgrp(), os.getsid(0))
-        # A fill value unlikely to be in `ids`
-        fill = -12345
-        if nbytes is not None:
-            # Extend the buffer so that it is exactly `nbytes` bytes long
-            buf.extend([fill] * (nbytes // intsize))
-            self.assertEqual(len(buf) * intsize, nbytes)   # sanity check
-        else:
-            buf.append(fill)
-        with open("/dev/tty", "rb") as tty:
-            r = fcntl.ioctl(tty, termios.TIOCGPGRP, buf, 1)
-        rpgrp = buf[0]
-        self.assertEqual(r, 0)
-        self.assertIn(rpgrp, ids)
-
-    def test_ioctl_mutate(self):
-        self._check_ioctl_mutate_len()
-
-    def test_ioctl_mutate_1024(self):
-        # Issue #9758: a mutable buffer of exactly 1024 bytes wouldn't be
-        # copied back after the system call.
-        self._check_ioctl_mutate_len(1024)
-
-    def test_ioctl_mutate_2048(self):
-        # Test with a larger buffer, just for the record.
-        self._check_ioctl_mutate_len(2048)
-
-    def test_ioctl_signed_unsigned_code_param(self):
-        if not pty or not hasattr(os, 'openpty'):
-            raise unittest.SkipTest('pty module required')
-        mfd, sfd = pty.openpty()
-        try:
-            if termios.TIOCSWINSZ < 0:
-                set_winsz_opcode_maybe_neg = termios.TIOCSWINSZ
-                set_winsz_opcode_pos = termios.TIOCSWINSZ & 0xffffffff
-            else:
-                set_winsz_opcode_pos = termios.TIOCSWINSZ
-                set_winsz_opcode_maybe_neg, = struct.unpack("i",
-                        struct.pack("I", termios.TIOCSWINSZ))
-            our_winsz = struct.pack("HHHH",80,25,0,0)
-            # test both with a positive and potentially negative ioctl code
-            new_winsz = fcntl.ioctl(mfd, set_winsz_opcode_pos, our_winsz)
-            new_winsz = fcntl.ioctl(mfd, set_winsz_opcode_maybe_neg, our_winsz)
-        finally:
-            os.close(mfd)
-            os.close(sfd)
-
-
-if __name__ == "__main__":
-    unittest.main()