BUG/MEDIUM: stream-int: Don't set MSG_MORE flag if no more data are expected

BUG/MEDIUM: stream-int: Don't set MSG_MORE flag if no more data are expected

In HTX, if the HTX_FL_EOI message is set on the message, we don't set the
CO_SFL_MSG_MORE flag on the connection. This way, the send is not delayed if
only the EOM is missing in the HTX message.

This patch depends on the commit "MEDIUM: htx: Add a flag on a HTX message when
no more data are expected".

This patch should partially fix the issue #756. It must be backported to
2.1. For earlier versions, CO_SFL_MSG_MORE is ignored by HTX muxes.