Update ESP-IDF c_char type

[SergioGasquez]

Description

Updates the c_chart type for ESP-IDF after rust-lang/rust#132975

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI
  • Still not tested, hence the PR is still in draft

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[tgross35]

Any reason this is marked as a draft?

[SergioGasquez]

@ivmarkov wanted to do a small test, that's why I marked it as draft until we confirm that it works, but if you think the change is small enough I can mark it as ready

[tgross35]

Happy to have tests! There probably won't be another release until next week anyway.