Add workaround for the issue #4571 in setuptools

setuptools version 72.2.0 contains the change that does not allow to
build C++ native extension for PyPy, because it does not provide the
LDCXXSHARED configuration variable:
https://github.com/pypa/setuptools/issues/4571

setup.py

@@ -3,6 +3,7 @@
 """
 import os
 import sys
+import sysconfig
 
 from setuptools import setup, Extension
 from setuptools.command.build_ext import build_ext
@@ -78,6 +79,17 @@ def get_environment_flag(name):
     pyitt_native_compiler_args.append('--coverage')
     pyitt_native_link_args.append('--coverage')
 
+# Workaround for issue #4571 in setuptools
+if sys.platform != 'win32':
+    LDSHARED_VAR_NAME = 'LDSHARED'
+    LDCXXSHARED_VAR_NAME = 'LDCXXSHARED'
+
+    if LDCXXSHARED_VAR_NAME not in sysconfig.get_config_vars() and LDCXXSHARED_VAR_NAME not in os.environ:
+        if LDSHARED_VAR_NAME in os.environ:
+            os.environ[LDCXXSHARED_VAR_NAME] = os.environ[LDSHARED_VAR_NAME]
+        else:
+            os.environ[LDCXXSHARED_VAR_NAME] = sysconfig.get_config_vars().get(LDSHARED_VAR_NAME, None)
+
 pyitt_native = Extension('pyitt.native',
                          sources=itt_source + pyitt_native_sources,
                          include_dirs=itt_include_dirs,