[libc-commits] [libc] [libc] fix clang-tidy llvm-header-guard warnings (PR #82679)

[Nick Desaulniers via libc-commits]

nickdesaulniers wrote:

Probably don't want header guards on assert.h: https://github.com/llvm/llvm-project/pull/83334

https://github.com/llvm/llvm-project/pull/82679