s390x support?

Please answer the following before submitting your issue:

Note: Please include any substantial examples (debug session output,
stacktraces, etc) as linked gists.

1. What version of Delve are you using (`dlv version`)?
2. What version of Go are you using? (`go version`)?
3. What operating system and processor architecture are you using?
4. What did you do?
5. What did you expect to see?
6. What did you see instead?

The issue contains only the standard report template and names no file, test, or entry point. First establish the Delve, Go, operating-system, and s390x details requested in the template, then identify the affected debugger components and define support-validation tests before deciding what done means.

Written by the indexing model from the issue text.