[libc-commits] [libc] [libc][math] undef `iscanonical` before defining it using `LLVM_LIBC_FUNCTION` macro (PR #110865)

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overmighty wrote:

> removes the static_assert since conversion from bool to int is well defined in C/C++.

Nit: removes the `static_cast` because implicit conversion from `bool` to `int` is defined in C++.

https://github.com/llvm/llvm-project/pull/110865