gh-116869: Fix test_cext for Free Threading (#117043)

Don't check for warnings on Free Threading.

Author: vstinner

Lib/test/test_cext/__init__.py

@@ -40,9 +40,11 @@ def test_build_c11(self):
     def test_build_c99(self):
         self.check_build('_test_c99_cext', std='c99')
 
+    @unittest.skipIf(support.Py_GIL_DISABLED, 'incompatible with Free Threading')
     def test_build_limited(self):
         self.check_build('_test_limited_cext', limited=True)
 
+    @unittest.skipIf(support.Py_GIL_DISABLED, 'broken for now with Free Threading')
     def test_build_limited_c11(self):
         self.check_build('_test_limited_c11_cext', limited=True, std='c11')
 

Lib/test/test_cext/setup.py

@@ -11,7 +11,7 @@
 
 
 SOURCE = 'extension.c'
-if not support.MS_WINDOWS:
+if not support.MS_WINDOWS and not support.Py_GIL_DISABLED:
     # C compiler flags for GCC and clang
     CFLAGS = [
         # The purpose of test_cext extension is to check that building a C