bpo-41282: (PEP 632) Deprecate distutils.sysconfig (partial implementation of the PEP) (GH-23142)

This change:
* merges `distutils.sysconfig` into `sysconfig` while keeping the original functionality and
* marks `distutils.sysconfig` as deprecated

https://bugs.python.org/issue41282

Author: frenzymadness

Doc/distutils/apiref.rst

@@ -1452,6 +1452,8 @@ name.
 
 .. module:: distutils.sysconfig
    :synopsis: Low-level access to configuration information of the Python interpreter.
+.. deprecated:: 3.10
+   :mod:`distutils.sysconfig` has been merged into :mod:`sysconfig`.
 .. moduleauthor:: Fred L. Drake, Jr. <[email protected]>
 .. moduleauthor:: Greg Ward <[email protected]>
 .. sectionauthor:: Fred L. Drake, Jr. <[email protected]>
@@ -1510,6 +1512,9 @@ for other parts of the :mod:`distutils` package.
    meaning for other platforms will vary.  The file is a platform-specific text
    file, if it exists. This function is only useful on POSIX platforms.
 
+The following functions are deprecated together with this module and they
+have no direct replacement.
+
 
 .. function:: get_python_inc([plat_specific[, prefix]])
 

Doc/library/sysconfig.rst

@@ -224,6 +224,7 @@ Other functions
 
    Return the path of :file:`Makefile`.
 
+
 Using :mod:`sysconfig` as a script
 ----------------------------------
 

Lib/distutils/extension.py

@@ -4,6 +4,7 @@
 modules in setup scripts."""
 
 import os
+import re
 import warnings
 
 # This class is really only used by the "build_ext" command, so it might
@@ -161,7 +162,7 @@ def read_setup_file(filename):
             line = file.readline()
             if line is None:                # eof
                 break
-            if _variable_rx.match(line):    # VAR=VALUE, handled in first pass
+            if re.match(_variable_rx, line):    # VAR=VALUE, handled in first pass
                 continue
 
             if line[0] == line[-1] == "*":