add loongarch64 support

[212dandan]

Please review. If you have any questions, you can contact me at any time.

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[johnbartholomew]

Hi. It appears these are changes to Rapid YAML (the copy of the code in the third_party directory) not to jsonnet itself.

It would be better to contribute these changes upstream to the Rapid YAML project (edit: actually to c4core), and then they can be included in jsonnet when we update the Rapid YAML version. You could also check whether Rapid YAML version 0.5.0 already supports this architecture - if so, then I expect jsonnet will pick it up soon (with PR #1134)

[johnbartholomew]

It seems someone has already opened a PR on the c4core project to add support for LoongArch: biojppm/c4core#119

[johnbartholomew]

Thanks for your contribution, however I'm going to close this as it is better to get this into Rapid YAML and not try to maintain a modified version of the Rapid YAML code within jsonnet.