adding support for s390x

[dilipgb]

Summary

jam cli support for s390x architecture to build stacks in packeto community stack for s390x.

Use Cases

The stack build through jam cli will be used by knative functions in future to build function code through buildpacks.

Checklist

• [yes] I have viewed, signed, and submitted the Contributor License Agreement.
• [yes] I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• [yes] I have added an integration test, if necessary.
• [yes] I have reviewed the styleguide for guidance on my code quality.
• [yes] I'm happy with the commit history on this PR (I have rebased/squashed as needed).

[linux-foundation-easycla]

• ✅login: dilipgb / (e73fbee)

The committers listed above are authorized under a signed CLA.

[dilipgb]

closes #338

[dilipgb]

@robdimsdale can you please help with reviewing the PR.

[sophiewigmore]

Hey @dilipgb have you been able to test this and see that the jam binary works as expected on s390x?

[dilipgb]

@sophiewigmore there are some test case failures on s390x. I will mark it draft PR till I fix those issues. Thanks for taking a look at it.

[mhdawson]

@dilipgb great to see you working on this. Do you know if anybody has a similar plan to do the required addition for PPC?

[valen-mascarenhas14]

Hi @mhdawson . I'll be handling this task for PPC .