Update mktime header declaration to match upstream LLVM libc.

[Prabhuk]

Fixes:#1971

[armandomontanez]

I'm guessing this isn't backwards-compatible with older toolchain distributions?

[kilograham]

.. which it needs to be

[Prabhuk]

Thanks for bringing up the compatibility question. I should've added the testing info to the PR description.
The change is compatible with the old toolchain revision.

I was able to use the current Clang toolchain revision - e894df6392beea3723627329009f3e6d51d16f47 against pico-sdk master branch with this PR's commit cherry-picked. The bazel build was completed successfully.

I believe adding a specifier in redeclaration is not considered a failure in c++. But I may have to defer this to a language lawyer.

[petrhosek]

mktime is now included in LLVM libc time.h header, so the correct solution here is to delete that declaration altogether, but we also need to bump the toolchain version in MODULE.bazel.

[petrhosek]

I opened #1976 which updates the toolchain.

[Prabhuk]

mktime is now included in LLVM libc time.h header, so the correct solution here is to delete that declaration altogether, but we also need to bump the toolchain version in MODULE.bazel.

That makes sense. @armandomontanez Will there ever be a case in Pigweed presubmits where the patches landed in the "develop" branch here be built with the toolchain revision mentioned in Pigweed's bazel source files?

[armandomontanez]

Not automatically. For now, we'll be manually revving the required version of the Pico SDK. There may come a day where we do builds against HEAD of develop to learn about breakages sooner, but that's a ways out.

[Prabhuk]

Not automatically. For now, we'll be manually revving the required version of the Pico SDK. There may come a day where we do builds against HEAD of develop to learn about breakages sooner, but that's a ways out.

Great! I'll close this PR. I'm assuming when we update the toolchain revision in Pigweed, we will update the PicoSDK revision which includes #1976 to get the presubmits to pass.