[SHELL32] Do not return -1 if a file is not valid or not found - ExtractIconEx()...

[SHELL32] Do not return -1 if a file is not valid or not found - ExtractIconEx() (#2113)

ExtractIconEx() returns the number of successfully extracted icons from a file. The routine may return 0 in case no icons could be extracted but it could also return 0 if the file is not a valid PE image file or the file couldn't be found.

PrivateExtractIcons and the internal USER32 routine, ICO_ExtractIconExW(), return -1 in such scenarios. The behaviour is correct however we do not want that ExtractIconEx() returns -1 as well as it doesn't comply with the general documentation. In such cases, simply return 0 as no successful icons have been extracted due to related file failures.

CORE-16535