bug#41242: Port feature/native-comp to Windows

[Eli Zaretskii]

> From: Nicolas Bértolo <nicolasbertolo@gmail.com>
> Date: Wed, 13 May 2020 16:26:57 -0300
> 
> * `package-delete` fails because it tries to delete the .eln file via
>   `delete-file`. This is impossible in Windows because it's generally 
> impossible
>   to delete files that have an open HANDLE in the system.

Is that the handle from LoadLibrary?  If so, cannot we close the
handle once the .eln file is loaded?

Thanks.