Fix various function prototypes

[Rolf Kalbermatter]

Vincent Béron wrote:

>MSDN says it's void
>http://msdn.microsoft.com/library/default.asp?url=/library/en-
>us/shellcc/platform/shell/reference/functions/shcocreateinstance.asp
>
>I don't have latest PSDK.
>
>This will need to be investigated some more (although I'm leaning
>towards HRESULT).

My own tests seem to indicate that the function really returns some
codes which are consistent with HRESULTs. Also my SDK (from February
2003) declares the functions as SHSTDAPI which is an abbreviation for "extern HRESULT __stdcall". So MSDN seems to be wrong here and besides
returning them anyhow in the implementation eventhough some clients
may ignore them based on MSDN documentation seems the correct way to
me!

Rolf Kalbermatter