pymalloc_alloc() now returns directly the pointer, return NULL on
memory allocation error.

allocate_from_new_pool() already uses NULL as marker for "allocation
failed".

(cherry picked from commit 18f8dcfa10d8a858b152d12a9ad8fa83b7e967f0)
(cherry picked from commit 30e5aff5fb0e3841107ddd4539a1f5b8521c80fb)

Fix the following warning with GCC 4.8.5:
Objects/obmalloc.c: warning: ‘no_sanitize_thread’ attribute directive ignored
(cherry picked from commit 7e479c82218450255572e3f5fa1549dc283901ea)

Co-authored-by: Hai Shi <shihai1992@gmail.com>

(cherry picked from commit f0be4bbb9b3cee876249c23f2ae6f38f43fa7495)

Co-authored-by: Inada Naoki <songofacandy@gmail.com>

* bpo-36389: _PyObject_IsFreed() now also detects uninitialized memory (GH-12770)

Replace _PyMem_IsFreed() function with _PyMem_IsPtrFreed() inline
function. The function is now way more efficient, it became a simple
comparison on integers, rather than a short loop. It detects also
uninitialized bytes and "forbidden bytes" filled by debug hooks
on memory allocators.

Add unit tests on _PyObject_IsFreed().

(cherry picked from commit 2b00db68554422ec37faba2a80179a0172df6349)

* bpo-36389: Change PyMem_SetupDebugHooks() constants (GH-12782)

Modify CLEANBYTE, DEADDYTE and FORBIDDENBYTE constants: use 0xCD,
0xDD and 0xFD, rather than 0xCB, 0xBB and 0xFB, to use the same byte
patterns than Windows CRT debug malloc() and free().

(cherry picked from commit 4c409beb4c360a73d054f37807d3daad58d1b567)

* bpo-9263: _PyObject_Dump() detects freed memory (GH-10061)

_PyObject_Dump() now uses an heuristic to check if the object memory
has been freed: log "<freed object>" in that case.

The heuristic rely on the debug hooks on Python memory allocators
which fills the memory with DEADBYTE (0xDB) when memory is
deallocated. Use PYTHONMALLOC=debug to always enable these debug
hooks.

(cherry picked from commit 82af0b63b07aa8d92b50098e382b458143cfc677)

* bpo-9263: Fix _PyObject_Dump() for freed object (#10661)

If _PyObject_Dump() detects that the object is freed, don't try to
dump it (exit immediately).

Enhance also _PyObject_IsFreed(): it now detects if the pointer
itself looks like freed memory.

(cherry picked from commit 2cf5d32fd9e61488e8b0be55a2e92a752ba8b06b)

This function may access memory which is mapped but is considered
free by libc allocator. It behaves so by design, therefore we
need to suppress sanitizer reports.

GCC doesn't support MSan, so disable only TSan for it.
(cherry picked from commit fd3a91cbf93dd7bd97f01add9c90075d63cd7316)

Co-authored-by: Alexey Izbyshev <izbyshev@ispras.ru>

Fix typos found by codespell in docs, docstrings, and comments.
(cherry picked from commit c3d9508ff22ece9a96892b628dd5813e2fb0cd80)

Co-authored-by: Leo Arias <leo.arias@canonical.com>

* Py_Main() now starts by reading Py_xxx configuration variables to
  only work on its own private structure, and then later writes back
  the configuration into these variables.
* Replace Py_GETENV() with pymain_get_env_var() which ignores empty
  variables.
* Add _PyCoreConfig.dump_refs
* Add _PyCoreConfig.malloc_stats
* _PyObject_DebugMallocStats() is now responsible to check if debug
  hooks are installed. The function returns 1 if stats were written,
  or 0 if the hooks are disabled. Mark _PyMem_PymallocEnabled() as
  static.

* Rename PyPathConfig structure to _PyPathConfig and move it to
  Include/internal/pystate.h
* Rename path_config to _Py_path_config
* _PyPathConfig: Rename program_name field to program_full_path
* Add assert(str != NULL); to _PyMem_RawWcsdup(), _PyMem_RawStrdup()
  and _PyMem_Strdup().
* Rename calculate_path() to pathconfig_global_init(). The function
  now does nothing if it's already initiallized.