BUG/MINOR: hlua: Rely on CF_EOI to detect end of message in HTTP applets

BUG/MINOR: hlua: Rely on CF_EOI to detect end of message in HTTP applets

applet:getline() and applet:receive() functions for HTTP applets must rely
on the channel flags to detect the end of the message and not on HTX
flags. It means CF_EOI must be used instead of HTX_FL_EOM.

It is important because the HTX flag is transient. Because there is no flag
on HTTP applets to save the info, it is not reliable. However CF_EOI once
set is never removed. So it is safer to rely on it. Otherwise, the call to
these functions hang.

This patch must be backported as far as 2.4.