Fix invalid function cast warnings with gcc 8
for method conventions different from METH_NOARGS, METH_O and
METH_VARARGS excluding Argument Clinic generated code.

* Rename Include/internal/ header files:

  * pyatomic.h -> pycore_atomic.h
  * ceval.h -> pycore_ceval.h
  * condvar.h -> pycore_condvar.h
  * context.h -> pycore_context.h
  * pygetopt.h -> pycore_getopt.h
  * gil.h -> pycore_gil.h
  * hamt.h -> pycore_hamt.h
  * hash.h -> pycore_hash.h
  * mem.h -> pycore_mem.h
  * pystate.h -> pycore_state.h
  * warnings.h -> pycore_warnings.h

* PCbuild project, Makefile.pre.in, Modules/Setup: add the
  Include/internal/ directory to the search paths of header files.
* Update includes. For example, replace #include "internal/mem.h"
  with #include "pycore_mem.h".

Add pyatomic.h to the VS project (it wasn't referenced).

Introduce a configure check for strsignal(3) which defines HAVE_STRSIGNAL for
signalmodule.c. Add some common signals on HP-UX. This change applies for
Windows and HP-UX.

* Expose the sigset_t converter via private API _Py_Sigset_Converter().
* Use Argument Clinic for parsing sigset_t in signalmodule.c.
* Raise ValueError instead OverflowError for integers out of
  the C long range.

Based on patch by Pablo Galindo Salgado.

Starting with glibc 2.27.9000-xxx, sigaddset() can return EINVAL for some
reserved signal numbers between 1 and NSIG.  The `range(1, NSIG)` idiom
is commonly used to select all signals for blocking with `pthread_sigmask`.
So we ignore the sigaddset() return value until we expose sigfillset()
to provide a better idiom.

Co-authored-by: Vajrasky Kok <sky.kok@speaklikeaking.com>

Bug report and patch by Jeroen Demeyer.

The _PyTime API handles detects overflow and is well tested.

Document that the signal will only be sent once if internal is equal
to zero.

* Remove Setup.config
* Always define WITH_THREAD for compatibility.

* Improve signal delivery

Avoid using Py_AddPendingCall from signal handler, to avoid calling signal-unsafe functions.

* Remove unused function

* Improve comments

* Use _Py_atomic API for concurrency-sensitive signal state

* Add blurb

* bpo-30807: signal.setitimer() may disable the timer by mistake

* Add NEWS blurb

* Improve signal delivery

Avoid using Py_AddPendingCall from signal handler, to avoid calling signal-unsafe functions.

* Remove unused function

* Improve comments

* Add stress test

* Adapt for --without-threads

* Add second stress test

* Add NEWS blurb

* Address comments @haypo

* bpo-16500: Allow registering at-fork handlers

* Address Serhiy's comments

* Add doc for new C API

* Add doc for new Python-facing function

* Add NEWS entry + doc nit

Before, it was possible to get the following sequence of
events (especially on Windows, where the C-level signal handler for
SIGINT is run in a separate thread):

- SIGINT arrives
- trip_signal is called
- trip_signal writes to the wakeup fd
- the main thread wakes up from select()-or-equivalent
- the main thread checks for pending signals, but doesn't see any
- the main thread drains the wakeup fd
- the main thread goes back to sleep
- trip_signal sets is_tripped=1 and calls Py_AddPendingCall to notify
  the main thread the it should run the Python-level signal handler
- the main thread doesn't notice because it's asleep

This has been causing repeated failures in the Trio test suite:
  https://github.com/python-trio/trio/issues/119

* bpo-6532: Make the thread id an unsigned integer.

From C API side the type of results of PyThread_start_new_thread() and
PyThread_get_thread_ident(), the id parameter of
PyThreadState_SetAsyncExc(), and the thread_id field of PyThreadState
changed from "long" to "unsigned long".

* Restore a check in thread_get_ident().

Patch by Masayuki Yamamoto, reviewed and rebased by Erik Bray.

This is a first step on the long road toward resupporting Cygwin, which does
not provide siginfo_t.si_band.

Also update the classmethod and staticmethod doc strings and comments to
match the RST documentation.

The signal module was using old-style module initialization with
potential NULL dereferencing.

CID 1295026

generated by Argument Clinic.  Patch by Petr Viktorin.

in places where Py_DECREF was used.

macro Py_SETREF.

signalmodule.c

Retry:

* signal.sigtimedwait()
* threading.Lock.acquire()
* threading.RLock.acquire()
* time.sleep()

Add _Py_fstat_noraise() function when a Python exception is not welcome.

All these functions only accept positive timeouts, so this change has no effect
in practice.

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

when interrupted by a signal not in the *sigset* parameter, if the signal
handler does not raise an exception. signal.sigtimedwait() recomputes the
timeout with a monotonic clock when it is retried.

Remove test_signal.test_sigwaitinfo_interrupted() because sigwaitinfo() doesn't
raise InterruptedError anymore if it is interrupted by a signal not in its
sigset parameter.

fstat() may fail with EOVERFLOW on files larger than 2 GB because the file size type is an signed 32-bit integer.

Detect integer overflow on the file descriptor of the socket on 64-bit Python.