shell32: iconcache.c: Add stub implementation for SHGetIconOverlayIndex[AW] (RESEND)

[Zac Brown]

Zac Brown wrote:
> Add stub implementation for SHGetIconOverlayIndex[AW].
> 
> Mentioned in Bug 7447, though it does not seem to need a full 
> implementation yet. Since its documented in MSDN, may as well add the 
> stub implementation of it.
> 
> 
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> 
> 
Error in my comments. Scratch it, sending another...