Auto merge of #128102 - Oneirical:real-testate, r=Kobzol

Migrate `extern-diff-internal-name`, `extern-multiple-copies` and `extern-multiple-copies2` `run-make` tests to rmake

Part of #121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).

Please try:

try-job: test-various

Author: bors