[pyOpenSSL] PATCH: Handle long serial numbers in X509 get_serial_number

[Leigh D. <le...@ec...>]

Hi all,

I've recently been looking at pyOpenSSL but I noticed that it didn't 
properly handle the serial numbers in the Verisign certificates that I'm 
using. The serial numbers are long - too big to fit in a 32-bit int, so 
OpenSSL returns -1 instead, which is passed through by pyOpenSSL.

This small patch handles these long serial numbers by converting them to 
strings, which are then converted to PyLong objects using the Python/C API.

Thanks
Leigh