[core] disable Nagle if streaming to backend
[core] disable Nagle if streaming to backend

disable Nagle algorithm if streaming to backend and content-length
is unknown at the point where lighttpd is about to begin sending
data to backend

lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4