[RSAENH] CPGetHashParam / Bug 5639 part 2

[Karsten Elfenbein]

Hi,

Same question for this one.

It fixes the case when CryptGetHashParam is called with pbData=NULL to
determine
the needed buffer size for the hash value.

It fixes the http://bugs.winehq.org/attachment.cgi?id=3024&action=view
testcase in http://bugs.winehq.org/show_bug.cgi?id=5639

Karsten