We require C99, so a configure test for this standard feature is not needed.

 #ifdef HAVE_DECLSPEC_DLL / #endif mismatch

Issue #29234: Inlining _PyStack_AsTuple() into callers increases their stack
consumption, Disable inlining to optimize the stack consumption.

Add _Py_NO_INLINE: use __attribute__((noinline)) of GCC and Clang.

It reduces the stack consumption, bytes per call, before => after:

test_python_call: 1040 => 976 (-64 B)
test_python_getitem: 976 => 912 (-64 B)
test_python_iterator: 1120 => 1056 (-64 B)

=> total: 3136 => 2944 (- 192 B)

Fix backward compatibility issue, HAVE_LONG_LONG was defined but empty, whereas
it is defined as 1 in Python 3.5.

(grafted from 4745d801cae2d57e3432313acd0b76b8b4cc9c75)

It's common to see these functions in the top 3 of "perf report".

When Python is not compiled with PGO, the performance of Python on call_simple
and call_method microbenchmarks depend highly on the code placement. In the
worst case, the performance slowdown can be up to 70%.

The GCC __attribute__((hot)) attribute helps to keep hot code close to reduce
the risk of such major slowdown. This attribute is ignored when Python is
compiled with PGO.

The following functions are considered as hot according to statistics collected
by perf record/perf report:

* _PyEval_EvalFrameDefault()
* call_function()
* _PyFunction_FastCall()
* PyFrame_New()
* frame_dealloc()
* PyErr_Occurred()

The original problem has been fixed in newer versions of FreeBSD.
Patch by Dimitry Andric of the FreeBSD project.

Patch by Ronald Oussoren.

api-level >= 23. Patch by Xavier de Gaye.

Issue #23524: Replace _PyVerify_fd function with calls to _set_thread_local_invalid_parameter_handler.

fstat(), these functions are always required.

Remove HAVE_STAT and HAVE_FSTAT defines, and stop supporting DONT_HAVE_STAT and
DONT_HAVE_FSTAT.

Patch from Andreas Schwab.

"format units" as legacy converters, as well as two new features:
"self converters" and the "version" directive.

Python now uses SipHash24 on all major platforms.

error messages and comments.

of arbitrary looking numbers.

by their HANDLE which is a pointer (and not a long, which is smaller).

as reported by Serhiy Storchaka and Matthew Barnett.

computation as the overflow behavior of signed integers is undefined.

In practice we require compiling everything with -fwrapv which forces overflow
to be defined as twos compliment but this keeps the code cleaner for checkers
or in the case where someone has compiled it without -fwrapv or their
compiler's equivalent.

Found by Clang trunk's Undefined Behavior Sanitizer (UBSan).

Cleanup only - no functionality or hash values change.