msi [3/12]: Assign the property to path if the property is empty

[Mike McCormack]

James Hawkins wrote:

> @@ -1456,6 +1456,9 @@ static void msi_dialog_update_pathedit( 
>      prop = msi_dialog_dup_property( dialog, control->property, indirect );
>  
>      path = msi_dup_property( dialog->package, prop );
> +    if (!path)
> +        path = prop;
> +
>      SetWindowTextW( control->hwnd, path );
>      SendMessageW( control->hwnd, EM_SETSEL, 0, -1 );

Later on in that code block, it does:

     msi_free( path );
     msi_free( prop );

If path and prop point to the same thing, then we'll try free and 
illegal pointer.

Looks like it would be better to replace msi_dup_property() with another 
(new) macro function that understands this behavior, rather than 
changing the code similarly in 4 places.

Mike