Add LoongArch64 build support

[4Darmygeometry]

Description of Change

Add LoongArch64 build support, LoongArch64 is a new ISA Cored By Loongson Technology LLC.

Bugs Fixed

• Fixes [FEATURE] LoongArch64 flavor of libSkiaSharp and libHarfBuzzSharp #3197

API Changes

None.

Behavioral Changes

None.

Required skia PR

None.

PR Checklist

• [√] Has tests (if omitted, state reason in description)
• [√] Rebased on top of main at time of PR
• [√] Merged related skia PRs
• [√] Changes adhere to coding standard
• [√] Updated documentation

[kasperk81]

it will be much easier to add this arch after #3200 goes in

[4Darmygeometry]

it will be much easier to add this arch after #3200 goes in

Suggest adding RISC-V 64 and LoongArch64 simultaneously

[kasperk81]

main change was in #3192, next is #3200 which makes both gnu and musl use the same clang cross script so x86_64 ci can build artifacts easily. once the second pr is merged, you can rebase and this pr will be very clean.

Suggest adding RISC-V 64 and LoongArch64 simultaneously

one benefit of keeping these changes separate is to track when things were added, with clean git history.

[4Darmygeometry]

/azp run

[azure-pipelines]

Commenter does not have sufficient privileges for PR 3198 in repo mono/SkiaSharp

[mattleibow]

/azp run

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[4Darmygeometry]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

@Catty2014

[mattleibow]

/azp run

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[kasperk81]

@mattleibow are you planning to merge this before #3200?

[kasperk81]

i started this work before them and they are just piggybacking. the decent thing to do is to wait for my work to finish..

[mattleibow]

I am not merging yet. I am just checking the build.
@4Darmygeometry can keep this open and rebase already on the PR by @kasperk81

Once we merge that, the diff will suddenly shrink.