This tries to mirror the following change.
```
commit c260fee516
Author: Gustavo Henrique Nihei <gustavo.nihei@espressif.com>
Date: Tue Aug 31 14:47:13 2021 -0300
libs/libxx: Enforce RTTI for building libcxxabi
It is okay for the application to be built without RTTI (-fno-rrti), but
libcxxabi requires RTTI at least for the library.
Signed-off-by: Gustavo Henrique Nihei <gustavo.nihei@espressif.com>
```