Enable to build using Clang 15

[bjosv]

The diagnostics in Clang 15 is stricter and finds some issues.

• [-Werror,-Wstrict-prototypes] Using a strict prototype for some main()'s in the test code.

• [-Werror,-Wunused-but-set-variable] The variable 'present_id' is set but not used, so removed.

Some details: https://reviews.llvm.org/D122895

[mikkelfj]

I have seen this main issue before. I generally just fix the main() call. Are there other places that are less trivial to fix?

As to the present_id, I'd like to understood this better. That code wasn't just added for no reason.

[bjosv]

Well, changing the 3 main's was a lot easier..thanks Regarding the present_id, the only thing I can find in the history was that it was used for a fprintf that was removed in https://github.com/dvidelabs/flatcc/commit/0dfe6219d53423f421469dacc5e6adc572d8987d

[mikkelfj]

Good find, seems reasonable to remove it. Ready to merge?

[bjosv]

Yes, I'm happy.