Add loongarch64 support

[Dandan336]

Hi maintainer,

Compiling the efibootguard failed for loong64 in the Debian Package Auto-Building environment.
Based on this commit, debian efibootguard was built successfully for loongarch64.
The details can be found at https://buildd.debian.org/status/logs.php?pkg=efibootguard&ver=0.18-1%2Bb1&arch=loong64.

Please review.

[jan-kiszka]

Thanks for this patch. Please note https://github.com/siemens/efibootguard/blob/master/CONTRIBUTING.md for our contribution process.

But also note that a purely compile-tested patch will not be accepted. We need functional tests. This is needed because issues may also be in our dependencies, most notably gnu-efi (see recent issues on arm32).

In the meantime, it is may be simpler to keep EFI Boot Guard disabled for loong64 on Debian. But the package maintainer can probably tell that better @gylstorffq.

[gylstorffq]

I added the patch for loongarch64 to package build for the version 0.16. The patch was also sent to the mailing list. If the package build breaks and we have no mainline support on loongarch64 it will be better to drop the patch and disable loongarch64 for efibootguard in debian.

[jan-kiszka]

Again, I don't want to block the new arch, but I do want someone actually testing what is being built. Bootloader, UKI stub, tooling, all that should be covered so that we can clarify the state of this support.