X509 vfy continued

Builds on @lvh's work in #1156. Let's see if jenkins is okay with it.
It doesn't look like they do based on the passing Jenkins tests but maybe we should change that to /* */ anyway...

On Sat, Jun 21, 2014 at 6:35 PM, Alex Gaynor <notifications@github.com>
wrote:

>> @@ -165,6 +181,11 @@
>>  """
>>  
>>  MACROS = """
>> +// X509_STORE_CTX
> Will comments in this style make Windows compiler mad?
> ---
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> https://github.com/pyca/cryptography/pull/1161/files#r14052385