[U-Boot] [U-Boot, v4, 05/14] efi: Makefile: Export variables for use with EFI

[Alexander Graf]

> When building an EFI app we need three things:
> 
>    - start-up code
>    - relocation code
>    - link script
> 
> These are all different for each architecture. We also need special
> compiler flags in some cases.
> 
> Add top-level Makefile variables for these along with documentation.
> 
> Signed-off-by: Simon Glass <sjg at chromium.org>

Thanks, applied to efi-next

Alex