BOOST_ASIO_DISABLE_CONCEPTS breaks compilation in co_composed.hpp

[5cript]

When BOOST_ASIO_DISABLE_CONCEPTS is defined https://github.com/chriskohlhoff/asio/blob/efdc25ab99786101351a5afb39f01dfaf0781401/asio/include/asio/co_composed.hpp#L848 will not build, because the concept is used unconditionally.