add test that len(memoryview) works

tests/memoryview/memoryviewattrs.pyx

@@ -260,6 +260,11 @@ def call():
 
     print (<int*>mv3._data)[0] , (<int*>mv2._data)[0] , (<int*>mv1._data)[0]
 
+    assert len(mv1) == 3
+    assert len(mv2) == 3
+    assert len(mv3) == 3
+
+
 @testcase
 def two_dee():
     u'''
@@ -272,6 +277,8 @@ def two_dee():
     cdef long[:,::1] mv1, mv2, mv3
     cdef array arr = array((2,2), sizeof(long), 'l')
 
+    assert len(arr) == 2
+
     cdef long *arr_data
     arr_data = <long*>arr.data