Thanks to Jelle Zijlstra for the patch.

* bpo-29243: Fix Makefile with respect to --enable-optimizations

When using the Profile Guided Optimization (./configure --enable-optimizations)
Python is built not only during `make` but rebuilt again during `make test`,
`make install` and others. This patch fixes the issue.

Note that this fix produces no change at all in the Makefile if configure is
run witout --enable-optimizations.

* !squash

Python/thread_foobar.h is the template code that is threading adaptation
for new platforms, also hasn't been used on actual platforms.
Python/thread_*.h give concrete examples of adaptation instead of the
template code.

ExpatParser.parse() of xml.sax.xmlreader now always closes the
source: close the file object or the urllib object if source is a
string (not an open file-like object). The change fixes a
ResourceWarning on parsing error.

Add test_parse_close_source() unit test.

It was possible to get a core dump by using uninitialized
_json objects. Now __new__ methods create initialized objects.
__init__ methods are removed.

Compiled regular expression objects with the re.LOCALE flag no longer
depend on the locale at compile time.  Only the locale at matching
time affects the result of matching.

Set the target to be 90% since there is enough OS-specific code and things that require manual testing that we will never hit 100%. Also turn off the status checks since they are so inconsistent in terms of flagging a PR as passing/failing that they aren't useful and can actually block merging from a phone.

The AST_H_DIR variable was removed from Makefile.pre.in by the commit
a5c62a8e (bpo-23404).

AST_H_DIR was hardcoded to "Include", so replace the removed variable
by its content.

Remove also ASDLGEN variable from sysconfig example since this
variable was also removed.

* bpo-30185: avoid KeyboardInterrupt tracebacks in forkserver

* Tweak comment

* bpo-30263: regrtest: log system load

* regrtest: log the number of CPUs

Log the number of CPUs in the header. --verbose now imply --header.

is_valid_fd() now uses fstat() instead of dup() on macOS to return 0
on a pipe when the other side of the pipe is closed. fstat() fails
with EBADF in that case, whereas dup() succeed.

Signed-off-by: Christian Heimes <christian@python.org>

Replace
   File "<stdin>", line 1, in ? 
with 
   File "<stdin>", line 1, in <module>

Don't rebuild generated files based on file modification time
anymore, the action is now explicit. Replace "make touch"
with "make regen-all".

Changes:

* Remove "make touch", Tools/hg/hgtouch.py and .hgtouch
* Add a new "make regen-all" command to rebuild all generated files
* Add subcommands to only generate specific files:

  - regen-ast: Include/Python-ast.h and Python/Python-ast.c
  - regen-grammar: Include/graminit.h and Python/graminit.c
  - regen-importlib: Python/importlib_external.h and Python/importlib.h
  - regen-opcode: Include/opcode.h
  - regen-opcode-targets: Python/opcode_targets.h
  - regen-typeslots: Objects/typeslots.inc

* Rename PYTHON_FOR_GEN to PYTHON_FOR_REGEN
* pgen is now only built by by "make regen-grammar"
* Add $(srcdir)/ prefix to paths to source files to handle correctly
  compilation outside the source directory

Note: $(PYTHON_FOR_REGEN) is no more used nor needed by "make"
default target building Python.

Run autoconf.

Don't test if .git/HEAD file exists, but only if the .git file (or
directory) exists.

There is no need to test for new-style classes versus classic classes in Python 3.

- Add NoReturn type
- Use WrapperDescriptorType (original PR by Jim Fasarakis-Hilliard)
- Minor bug-fixes

* bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux

* Add NEWS entry

decriptor -> descriptor

FileIO.seek() and FileIO.tell() method now set the internal seekable
attribute to avoid one syscall on open() (in buffered or text mode).

The seekable property is now also more reliable since its value is
set correctly on memory allocation failure.

AsyncoreEchoServer of test_ssl now calls
asyncore.close_all(ignore_all=True) to ensure that
asyncore.socket_map is cleared once the test completes, even if
ConnectionHandler was not correctly unregistered.

Fix the following warning:

Warning -- asyncore.socket_map was modified by test_ssl
  Before: {}
  After:  {6: <test.test_ssl.AsyncoreEchoServer.EchoServer.ConnectionHandler>}

BuildExtTestCase of test_distutils now uses support.temp_cwd() in
setUp() to remove files created in the current working in all
BuildExtTestCase unit tests, not only test_build_ext().

Move also tearDown() just after setUp().

* #30190 / unittest / assertAlmostEqual(delta=...) / error msg: show the difference between the 2 numbers in case of failure

* safe_repr() diff

* also show difference when passing 'places' argument

* refactoring

* update Misc/NEWS