[libc-commits] [libc] [libc] start fix readability-identifier-naming lints (PR #83342)

[Nick Desaulniers via libc-commits]

nickdesaulniers wrote:

> > constexpr
> 
> https://clang.llvm.org/extra/clang-tidy/checks/readability/identifier-naming.html#cmdoption-arg-ConstexprFunctionCase

Adding this will result in a whole host of other changes, since we're internally inconsistent at the moment.

```
$ ninja -k2000 libc-lint 2>&1 | grep readability-identifier-naming | grep 'constexpr function' | sort -u | wc -l
170
```
:)

https://github.com/llvm/llvm-project/pull/83342