void put_eof( error_code& ec);
In certain cases, HTTP needs to know where the end of the stream is. For
example, sometimes servers send responses without Content-Length and expect
the client to consume input (for the body) until EOF. Callbacks and errors
will still be processed as usual. This is typically called when a read
from the underlying stream object sets the error code to
Only valid after parsing a complete header.
Set to the error, if any occurred.