Add also a new _PyTime_AsMicroseconds() function.

threading.TIMEOUT_MAX is now be smaller: only 292 years instead of 292,271
years on 64-bit system for example. Sorry, your threads will hang a *little
bit* shorter. Call me if you want to ensure that your locks wait longer, I can
share some tricks with you.

I didn't notice that the ssl module uses private attributes of socket objects.

* _PyTime_AsTimeval() now ensures that tv_usec is always positive
* _PyTime_AsTimespec() now ensures that tv_nsec is always positive
* _PyTime_AsTimeval() now returns an integer on overflow instead of raising an
  exception

Move Py_BEGIN_ALLOW_THREADS/Py_END_ALLOW_THREADS inside internal_select_ex() to
prepare a switch to the _PyTime_t type and retry syscall on EINTR.

* Add _PyTime_AsTimespec()
* Add unit tests for _PyTime_AsTimespec()

* Add _PyTime_GetSystemClockWithInfo()

* Add _PyTime_FromNanoseconds()
* Add _PyTime_AsSecondsDouble()
* Add unit tests for _PyTime_AsSecondsDouble()

* Rename _PyTime_FromObject() to _PyTime_FromSecondsObject()
* Add _PyTime_AsNanosecondsObject() and _testcapi.pytime_fromsecondsobject()
* Add unit tests

Use time.gmtime() instead of time.sleep(), because time.sleep() is no more
declared with METH_VARARGS but with METH_O. time.gmtime() is still declared
with METH_VARARGS and so it is called with PyCFunction_Call() which is the
target of the test_gdb unit test.

-Og does not optimize the C code, it's just "fast debugging".

sigtimedwait([], timeout) fails with OSError(EINVAL) on OpenIndiana, wait for a
signal which will never be received instead.

GetTickCount64() is now always available.

In practice, _PyTime_t is a number of nanoseconds. Its C type is a 64-bit
signed number. It's integer value is in the range [-2^63; 2^63-1]. In seconds,
the range is around [-292 years; +292 years]. In term of Epoch timestamp
(1970-01-01), it can store a date between 1677-09-21 and 2262-04-11.

The API has a resolution of 1 nanosecond and use integer number. With a
resolution on 1 nanosecond, 64-bit IEEE 754 floating point numbers loose
precision after 194 days. It's not the case with this API. The drawback is
overflow for values outside [-2^63; 2^63-1], but these values are unlikely for
most Python modules, except of the datetime module.

New functions:

- _PyTime_GetMonotonicClock()
- _PyTime_FromObject()
- _PyTime_AsMilliseconds()
- _PyTime_AsTimeval()

This change uses these new functions in time.sleep() to avoid rounding issues.

The new API will be extended step by step, and the old API will be removed step
by step. Currently, some code is duplicated just to be able to move
incrementally, instead of pushing a large change at once.

add a version changed note in modified functions.

in debug mode to detect bugs earlier.

_PyUnicodeWriter_Finish() doesn't check if the read only string is consistent,
whereas it does check consistency for strings built by itself.

as repr().

creation) mode.

close the binary file to fix a resource warning.

Flushing sys.stdout and sys.stderr in Py_FatalError() can call again
Py_FatalError(). Add a reentrant flag to detect this case and just abort at the
second call.

writer failed in BufferedRWPair.close().