pythongh-126876: Fix test_socket.testLargeTimeout() for missing _testcapi (python#127517)

(cherry picked from commit c46acd3)

Author: vstinner

Lib/test/test_socket.py

@@ -5130,7 +5130,10 @@ def testLargeTimeout(self):
         # gh-126876: Check that a timeout larger than INT_MAX is replaced with
         # INT_MAX in the poll() code path. The following assertion must not
         # fail: assert(INT_MIN <= ms && ms <= INT_MAX).
-        large_timeout = _testcapi.INT_MAX + 1
+        if _testcapi is not None:
+            large_timeout = _testcapi.INT_MAX + 1
+        else:
+            large_timeout = 2147483648
 
         # test recv() with large timeout
         conn, addr = self.serv.accept()
@@ -5145,7 +5148,10 @@ def testLargeTimeout(self):
 
     def _testLargeTimeout(self):
         # test sendall() with large timeout
-        large_timeout = _testcapi.INT_MAX + 1
+        if _testcapi is not None:
+            large_timeout = _testcapi.INT_MAX + 1
+        else:
+            large_timeout = 2147483648
         self.cli.connect((HOST, self.port))
         try:
             self.cli.settimeout(large_timeout)