[stable] druntime: Fix malloc-leaks in ModuleGroup.sortCtors()

[kinke]

I guess the recent removal of module constructors in druntime has brought these to light, for a little LDC ASan smoke test, which newly complains with D v2.105, e.g.:

Direct leak of 78624 byte(s) in 126 object(s) allocated from:
#0 0x55606978c40d in malloc /local/mnt/workspace/tmp/final/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:145:3
#1 0x5560698050b1 in _D2rt5minfo11ModuleGroup9sortCtorsMFNbAyaZv

[dlang-bot]

Thanks for your pull request and interest in making D better, @kinke! We are looking forward to reviewing it, and you should be hearing from a maintainer soon.
Please verify that your PR follows this checklist:

• My PR is fully covered with tests (you can see the coverage diff by visiting the details link of the codecov check)
• My PR is as minimal as possible (smaller, focused PRs are easier to review than big ones)
• I have provided a detailed rationale explaining my changes
• New or modified functions have Ddoc comments (with Params: and Returns:)

Please see CONTRIBUTING.md for more information.

---

If you have addressed all reviews or aren't sure how to proceed, don't hesitate to ping us with a simple comment.

Bugzilla references

Your PR doesn't reference any Bugzilla issue.

If your PR contains non-trivial changes, please reference a Bugzilla issue or create a manual changelog.

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "stable + dmd#15559"

[ljmf00]

Hey, I actually got this at my ASAN checks at work, I disables leakage due to this. I didnt get into it but thanks for going through this! 😊

[RazvanN7]

Thanks!