wintrust: Don't expect ImageGetCertificateData to succeed when Certificate is NULL

[Juan Lang]

This fixes the regression in iTunes described in bug 10803.
--Juan
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: 0005-Don-t-expect-ImageGetCertificateData-to-succeed-when-Certificate-is-NULL.txt
Url: http://www.winehq.org/pipermail/wine-patches/attachments/20080114/13a47251/attachment.txt