BUG/MINOR: tcpcheck: Disable QUICKACK only if data should be sent after connect

It is only a real problem for agent-checks when there is no agent string to
send. The condition to disable TCP_QUICKACK was only based on the action
type following the connect one. But it is not always accurate. indeed, for
agent-checks, there is always a SEND action. But if there is no "agent-send"
string defined, nothing is sent. In this case, this adds 200ms of latency
with no reason.

To fix the bug, a flag is now used on the CONNECT action to instruct there
are data that should be sent after the connect. For health-checks, this flag
is set if the action following the connect is a SEND action. For
agent-checks, it is set if an "agent-send" string is defined.

This patch should fix the issue #1836. It must be backported as far as 2.2.

(cherry picked from commit 871dd82117f1e9a673938c6987ddf8989485d384)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 549dc891e949aef086102b04a2bc530cb6457722)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 3971f8a33d27c599e6af6688db3ce80eb4280980)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
3 files changed