[clang] clang_EvalResult_getAsCXString impl (PR #134551)

[via cfe-commits]

cor3ntin wrote:

@AaronBallman I missed most of the discussion here, but the underlying object is an array.  Trying to find the null terminator once the pointer has decayed is asking for trouble. Is there a way to evaluate as an array? If not, that might be a better direction. That would be less awkward to use (and in that case the array would contain the whole string, including embedded and terminal nulls)

https://github.com/llvm/llvm-project/pull/134551