> +CPPFLAGS+= -D_LIBCXXABI_FORGIVING_DYNAMIC_CAST

Got curious why OpenBSD platform needs some modifications for most of
the things in C/C++.
And found this [1], with a copious explanation as a comment, then the
code implementation.
I don't understant it but I am happy I don't have to work in this high
programming language.
Sorry for hijacking the thread.

Out of curiosity again, is anyone among the OpenBSD devs who can fully
understand this?

[1] https://github.com/llvm-mirror/libcxxabi/blob/master/src/private_typeinfo.cpp