[Pyrex] casting warning

[Eric Huss]

The following snippet of code generates warnings when compiled by gcc:

cdef class A:

    cdef foo(self):
        print 'A.foo'

cdef class B(A):

    cdef foo(self):
        print 'B.foo'

test.c: In function `__pyx_tp_new_4test_B':
test.c:267: warning: assignment from incompatible pointer type


This only happens when you subclass something that has a cdef function and
redefine it.  It seems benign, but I as wondering if anyone has figured
out a fix.  It looks like the cast for the vtable assignment is simply
using the wrong type (perhaps should be using its base_type?).

-Eric