Remove the port
If a port exists, it is removed. The rest of the authority is unchanged.
assert( url( "http://www.example.com:80" ).remove_port().authority().buffer() == "www.example.com" );
this->has_port() == false && this->port_number() == 0 && this->port() == ""
Linear in `this->size()`.
Throws nothing.
authority = [ userinfo "@" ] host [ ":" port ]
port = *DIGIT