Use sysconfig module instead of distutils.sysconfig for python >= 3.9 (…

…GH-5761)

See #5751

Cython/Build/BuildExecutable.py

@@ -13,13 +13,26 @@
 
 import sys
 import os
-from distutils import sysconfig
+if sys.version_info < (3, 9):
+    from distutils import sysconfig as _sysconfig
+
+    class sysconfig(object):
+
+        @staticmethod
+        def get_path(name):
+            assert name == 'include'
+            return _sysconfig.get_python_inc()
+
+        get_config_var = staticmethod(_sysconfig.get_config_var)
+else:
+    # sysconfig can be trusted from cpython >= 3.8.7
+    import sysconfig
 
 
 def get_config_var(name, default=''):
     return sysconfig.get_config_var(name) or default
 
-INCDIR = sysconfig.get_python_inc()
+INCDIR = sysconfig.get_path('include')
 LIBDIR1 = get_config_var('LIBDIR')
 LIBDIR2 = get_config_var('LIBPL')
 PYLIB = get_config_var('LIBRARY')

Cython/Parser/ConcreteSyntaxTree.pyx

@@ -25,7 +25,19 @@ cdef extern from "parsetok.h":
         perrdetail * err_ret,
         int * flags)
 
-import distutils.sysconfig
+if sys.version_info < (3, 9):
+    from distutils import sysconfig as _sysconfig
+
+    class sysconfig(object):
+
+        @staticmethod
+        def get_path(name):
+            assert name == 'include'
+            return _sysconfig.get_python_inc()
+else:
+    # sysconfig can be trusted from cpython >= 3.8.7
+    import sysconfig
+
 import os
 import re
 
@@ -47,7 +59,7 @@ cdef dict type_names = {}
 cdef print_tree(node* n, indent=""):
     if not type_names:
         type_names.update(extract_names(
-            os.path.join(distutils.sysconfig.get_python_inc(), 'token.h')))
+            os.path.join(sysconfig.get_path('include'), 'token.h')))
         type_names.update(extract_names(
             os.path.join(os.path.dirname(__file__), 'graminit.h')))