The new {b,l}p_{u,}longlong() didn't check get_pylong()'s return for NULL.

Repaired that, and added appropriate tests for it to test_struct.py.

Lib/test/test_struct.py

@@ -314,4 +314,10 @@ def test_std_qQ():
                     pass
                 test_one_qQ(x)
 
+    # Some error cases.
+    for direction in "<>":
+        for letter in "qQ":
+            for badobject in "a string", 3+42j, randrange:
+                any_err(struct.pack, direction + letter, badobject)
+    
 test_std_qQ()