Make uuid1 and uuid4 tests conditional on whether ctypes can be imported;

implementation of either function depends on ctypes but uuid as a whole does
not.

Lib/test/test_uuid.py

@@ -367,6 +367,12 @@ def test_getnode(self):
         self.assertEqual(node1, node2)
 
     def test_uuid1(self):
+        # uuid1 requires ctypes.
+        try:
+            import ctypes
+        except ImportError:
+            return
+
         equal = self.assertEqual
 
         # Make sure uuid1() generates UUIDs that are actually version 1.
@@ -420,6 +426,12 @@ def test_uuid3(self):
             equal(str(u), v)
 
     def test_uuid4(self):
+        # uuid4 requires ctypes.
+        try:
+            import ctypes
+        except ImportError:
+            return
+
         equal = self.assertEqual
 
         # Make sure uuid4() generates UUIDs that are actually version 4.