Correct check after memory allocation.

ppenum is already tested for NULL at the beginning of the function.
What is intended here is to know if the memory allocation succeeded.

Found by cppcheck.

Change-Id: I31a3bed93b5dfe1a4d384478267f7c8cc0421181

dtrans/source/win32/dtobj/XTDataObject.cxx

@@ -832,7 +832,7 @@ STDMETHODIMP CEnumFormatEtc::Clone( IEnumFORMATETC** ppenum )
         return E_INVALIDARG;
 
     *ppenum = new CEnumFormatEtc( m_lpUnkOuter, m_FormatEtcContainer );
-    if ( NULL != ppenum )
+    if ( NULL != *ppenum )
         static_cast< LPUNKNOWN >( *ppenum )->AddRef( );
 
     return ( NULL != *ppenum ) ? S_OK : E_OUTOFMEMORY;