Fix Clang CFI icall type mismatch in rd_list_remove_cmp and string comparators

[Eric Xu (EricFXU)]

Problem

Under Clang Control Flow Integrity (-fsanitize=cfi-icall), function pointer signatures at indirect call sites must match the target function parameter types exactly.

Passing (void *)strcmp or comparators without const parameters to rd_list_remove_cmp and rd_list_find causes Clang CFI to flag due to type mismatches between int (*)(void *, void *) and int (*)(const void *, const void *).

Fix

1. Updated rd_list_remove_cmp and rd_list_remove_multi_cmp signatures in src/rdlist.h and src/rdlist.c to accept int (*cmp)(const void *_a, const void *_b).
2. Replaced (void *)strcmp function pointer casts with rd_list_cmp_str in src/rdkafka_metadata.c, src/rdkafka_partition.c, src/rdkafka_topic.c, and src/rdkafka_sasl_oauthbearer.c.

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[Ankith L (Ankith-Confluent)]

Thanks for the PR Eric Xu (@EricFXU).
I've added a few comments.
Once those are addressed we can run the CI and see if anything else comes up.

[Ankith L (Ankith-Confluent)]

/sem-approve

[Ankith L (Ankith-Confluent)]

Hi Eric Xu (@EricFXU)
There are few style fixes
Could you run make style-fix to resolve it.

[Eric Xu (EricFXU)]

Hi Ankith L (@Ankith-Confluent), I had installed the wrong version of cmake (pip install installed 18.1.18), and I realized style-format.sh only checks the major version number is set to 18. With the help of AI, checked and confirmed the dockerfile's image has ubuntu:24.04 , which uses 18.1.3 version. After installing this version, I think the make style-fix runs the right format. Please LMK if this doesn't pass and I can try something else.

Also, could you please help answer when we can expect this fix to be released?

[Ankith L (Ankith-Confluent)]

/sem-approve

[Ankith L (Ankith-Confluent)]

Hey Eric Xu (@EricFXU)
The dates on the release is not finalised yet, but it should be by the end of the month.

[Ankith L (Ankith-Confluent)]

Thanks for the PR Eric Xu (@EricFXU)
LGTM!

We will be merging it after another round of review.