bigfile/py: We cannot use memoryview for py2 even on 2.7.10

Because numpy.ndarray does not accept it as buffer= argument

    https://github.com/numpy/numpy/issues/5935

and our memcpy crashes.

NOTE if we'll need to use memoryview, we can adapt our memcpy to use
array() directly which works with memoryview, as outlined in the above
numpy issue.

bigfile/_bigfile.c

@@ -41,10 +41,15 @@ typedef struct _frame PyFrameObject;
  * on python2 < 2.7.10 memoreview object is not accepted in a lot of
  * places, see e.g. http://bugs.python.org/issue22113 for struct.pack_into()
  *
+ * also on python 2.7.10, even latest numpy does not accept memoryview as
+ * buffer for ndarray: https://github.com/numpy/numpy/issues/5935
+ *
  * if we know memoryview won't be accepted - we pass old buffer
  *
  * TODO get rid of this and eventually use only memoryview  */
-#define BIGFILE_USE_OLD_BUFFER  (PY_VERSION_HEX < 0x02070AF0)
+//#define BIGFILE_USE_OLD_BUFFER  (PY_VERSION_HEX < 0x02070AF0)
+// waiting for numpy to start accept it on python2
+#define BIGFILE_USE_OLD_BUFFER  (PY_VERSION_HEX < 0x03000000)
 
 
 /*