z/OS Compatibility

• Please check this box if this contribution uses AI-generated content (including content generated by GitLab Duo features) as outlined in the GitLab DCO & CLA. As a benefit of being a GitLab Community Contributor, you receive complimentary access to GitLab Duo.

What does this MR do?

This MR makes changes that are necessary for Runner to work on z/OS.

Why was this MR needed?

Currently, we rely on git patches to make changes to the Runner source code that live in another repo. By integrating the compatibility changes directly into this repo, we can address any problems or changes that need to be made in a better fashion.

## What's the best way to test this MR?

## What are the relevant issue numbers?