`openssl_stream` / `wolfssl_stream` move operations leave `impl_->s_` dangling

[ashtum]

The move constructor and move assignment operator of openssl_stream / wolfssl_stream leave the internal impl::s_ reference bound to the source object's stream_, not the destination's.

#include <boost/capy.hpp>
#include <boost/corosio/openssl_stream.hpp>
#include <boost/corosio/tcp_socket.hpp>
#include <boost/corosio/io_context.hpp>

using namespace boost;

capy::task<>
async_main()
{
    corosio::tls_context ctx;
    corosio::tcp_socket sock(co_await capy::this_coro::executor);
    corosio::openssl_stream a(&sock, ctx);
    corosio::openssl_stream b(std::move(a)); // b.impl_->s_ now references a.stream_
    co_await b.handshake(corosio::openssl_stream::client); // UB
}

int
main()
{
    corosio::io_context ioc;
    capy::run_async(ioc.get_executor())(async_main());
    ioc.run();
}