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
diff --git a/Lib/distutils/extension.py b/Lib/distutils/extension.py
index c507da3..e85032e 100644
--- a/Lib/distutils/extension.py
+++ b/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] == "*":