tests: Rename "array" module to "uarray".

tests/basics/array_intbig.py

@@ -1,10 +1,13 @@
 # test array types QqLl that require big-ints
 
 try:
-    from array import array
+    from uarray import array
 except ImportError:
-    print("SKIP")
-    raise SystemExit
+    try:
+        from array import array
+    except ImportError:
+        print("SKIP")
+        raise SystemExit
 
 print(array('L', [0, 2**32-1]))
 print(array('l', [-2**31, 0, 2**31-1]))