[libc-commits] [libc] [libc][cmake] move _get_hermetic_test_compile_options to LLVMLibCTestRules.cmake (PR #122549)

[Nick Desaulniers via libc-commits]

nickdesaulniers wrote:

I should move `_get_common_test_compile_options`, too for all of the same reasons.

https://github.com/llvm/llvm-project/pull/122549