[PATCH] GetUrlCacheEntryInfo*: Handle null dest pointer when length is given

[Jon Griffiths]

> Internal functions should return an error code instead of
> calling SetLastError.

Perhaps in a general sense, but URLCache_CopyEntry already did
SetLastError(ERROR_INSUFFICIENT_BUFFER): setting it there means the
4 places that call it don't need to ^ the logic to set the 2
different errors themselves.

^ "repeat" is probably the word I was looking for there :-)