Construct an acceptor without opening it.
template< typename ExecutionContext> basic_socket_acceptor( ExecutionContext & context, typename constraint< is_convertible< ExecutionContext &, execution_context & >::value >::type = 0);
This constructor creates an acceptor without opening it to listen for
new connections. The
open() function must be called before
the acceptor can accept new socket connections.
An execution context which provides the I/O executor that the acceptor will use, by default, to dispatch handlers for any asynchronous operations performed on the acceptor.