Make _private_h_line respect drawing target

[DPS2004]

Thank you for your contribution to the Fake-08 Before submitting this PR, please make sure:

• [x] This pull request is for a single Feature or BugFix
• [x] Your code builds clean without any errors on all platforms
• [ ] You have added unit tests (if this is a change to the core Pico 8 emulator)

Fixes https://github.com/jtothebell/fake-08/issues/223

[briaguya-ai]

Tested by grabbing the miyoo libretro core from https://github.com/DPS2004/fake-08/actions/runs/7048216067 and manually replacing the one in the /RetroArch/.retroarch/cores directory and it's working perfectly!