Re: ole32: don't crash when running the marshal tests on Vista.

[Rob Shearman]

2008/7/30 Reece Dunn :
> When running the ole32:marshal tests on Vista, the call to
> CoUnmarshalInterface fails. This results in pProxy being NULL which
> then causes the crash on the QueryInterface call.
>
> This patch makes sure that the pProxy-dependant tests are only called
> when pProxy is valid.

We need to work out why the test is failing - possibly it requires
more implementation of the object we are marshalling than in previous
versions of Windows.

Also, the typical way of detecting failure in our COM code in Wine is
to check the return value rather than whether a output object is NULL
or not.