libcxxrt seems to lack some features that are present in libc++abi

[Oleg Lelchuk]

libcxxrt seems to lack some features that are present in libc++abi. If I
compile this code and link it against libcxxrt:

#include <iostream>
#include <boost/type_index.hpp>

int main()
{
        int&& ref{4};
        std::cout <<
boost::typeindex::type_id_with_cvr<decltype(ref)>().pretty_name() <<
std::endl;
}

Then I get the message: "Abort (core dumped)". But if I link this code
against libc++abi, then I get

the output "int&&". It seems to me libcxxrt doesn't know how to deal
with rvalue references.