[compiler-rt] [asan] Build the asan_new_delete.cpp C++ slice with -frtti (PR #213077)

[David Justo via llvm-commits]

https://github.com/davidmrdavid commented:

(sorry for the delay here, hoping to get some momentum back here).

The change mostly LGTM, but we should ensure the CMake is compatible with MSVC. Please see my feedback about `append_rtti_flag` and consider my rephrasing of your comment. Thanks!

https://github.com/llvm/llvm-project/pull/213077