return more compliant values for usage in PrivateExtractIcons and PrivateExtractIconEx
    accept and fill in the icon identifier array correctly if provided
    allow to retrieve both small and large icons together.
- Simplify PrivateExtraxtIcons
- Modify PrivateExtractIconExW to:
   use compatible signature to ExtractIconEx in shell32 which it really is directly
     as tested on W2K by calling both functions with the same parameters
   directly call internal extraction function
   fix error when requesting 1 icon for both sizes