shell32: check result of HeapAlloc(), revised

[hto at mail.cnt.ru]

James Hawkins wrote:
> Please don't change the indentation.  You have to stick with whatever
> indentation exists for the file you're editing.

I have changed the indentation of IEnumFORMATETC_Constructor() and 
IDataObject_Constructor() to be more consistent with the rest of 
dataobject.c, which uses different indentation style.