mapi32: Write-strings warnings fix

[Alexandre Julliard]

Andrew Talbot <Andrew.Talbot at talbotville.com> writes:

> @@ -113,8 +114,8 @@
>      }
>      if (message->nFileCount) FIXME("Ignoring attachments\n");
>  
> -    subject = message->lpszSubject ? message->lpszSubject : "";
> -    body = message->lpszNoteText ? message->lpszNoteText : "";
> +    subject = message->lpszSubject ? message->lpszSubject : empty;
> +    body = message->lpszNoteText ? message->lpszNoteText : empty;

These are not part of a Win32 API structure, there's no reason they
can't be made const.

-- 
Alexandre Julliard
julliard at winehq.org