Add a note about using the new AST module.

to ease standalone use of the algorithm.

more robust.

It would be great if someone could review both sematics, markup, and
spelling, and correct the versionadded and versionchanges markers.

PyDict_Get/SetItemString.

ctypes maintains thread-local storage that has space for two error
numbers: private copies of the system 'errno' value and, on Windows,
the system error code accessed by the GetLastError() and
SetLastError() api functions.

Foreign functions created with CDLL(..., use_errno=True), when called,
swap the system 'errno' value with the private copy just before the
actual function call, and swapped again immediately afterwards.  The
'use_errno' parameter defaults to False, in this case 'ctypes_errno'
is not touched.

On Windows, foreign functions created with CDLL(...,
use_last_error=True) or WinDLL(..., use_last_error=True) swap the
system LastError value with the ctypes private copy.

The values are also swapped immeditately before and after ctypes
callback functions are called, if the callbacks are constructed using
the new optional use_errno parameter set to True: CFUNCTYPE(...,
use_errno=TRUE) or WINFUNCTYPE(..., use_errno=True).

New ctypes functions are provided to access the ctypes private copies
from Python:

- ctypes.set_errno(value) and ctypes.set_last_error(value) store
  'value' in the private copy and returns the previous value.

- ctypes.get_errno() and ctypes.get_last_error() returns the current
  ctypes private copies value.

(I didn't regen configure, since I don't have a working autoconf.)

for ctypes instances.  Closes issue #2404.

for ctypes instances.  Closes issue #2404.

This patch adds a new configure argument on OSX:
        --with-universal-archs=[32-bit|64-bit|all]

When used with the --enable-universalsdk option this controls which
CPU architectures are includes in the framework. The default is 32-bit,
meaning i386 and ppc. The most useful alternative is 'all', which includes
all 4 CPU architectures supported by MacOS X (i386, ppc, x86_64 and ppc64).

This includes limited support for the Carbon bindings in 64-bit mode as well,
limited because (a) I haven't done extensive testing and (b) a large portion
of the Carbon API's aren't available in 64-bit mode anyway.

I've also duplicated a feature of Apple's build of python: setting the
environment variable 'ARCHFLAGS' controls the '-arch' flags used for building
extensions using distutils.

convention that allows safe access to errno)

This code does not yet work on OS X (__thread storage specifier not
available), so i needs a configure check plus a more portable
solution.

errno (and LastError, on Windows).

ctypes maintains a module-global, but thread-local, variable that
contains an error number; called 'ctypes_errno' for this discussion.
This variable is a private copy of the systems 'errno' value; the copy
is swapped with the 'errno' variable on several occasions.

Foreign functions created with CDLL(..., use_errno=True), when called,
swap the values just before the actual function call, and swapped
again immediately afterwards.  The 'use_errno' parameter defaults to
False, in this case 'ctypes_errno' is not touched.

The values are also swapped immeditately before and after ctypes
callback functions are called, if the callbacks are constructed using
the new optional use_errno parameter set to True: CFUNCTYPE(..., use_errno=TRUE)
or WINFUNCTYPE(..., use_errno=True).

Two new ctypes functions are provided to access the 'ctypes_errno'
value from Python:

- ctypes.set_errno(value) sets ctypes_errno to 'value', the previous
  ctypes_errno value is returned.

- ctypes.get_errno() returns the current ctypes_errno value.

---

On Windows, the same scheme is implemented for the error value which
is managed by the GetLastError() and SetLastError() windows api calls.

The ctypes functions are 'ctypes.set_last_error(value)' and
'ctypes.get_last_error()', the CDLL and WinDLL optional parameter is
named 'use_last_error', defaults to False.

---

On Windows, TlsSetValue and TlsGetValue calls are used to provide
thread local storage for the variables; ctypes compiled with __GNUC__
uses __thread variables.