MINOR: flt-spoe: Report end of input immediately after applet init

MINOR: flt-spoe: Report end of input immediately after applet init

The SPOE applet forwards the message that must be sent to agent during its
init stage. So just after it is created. When it is performed, the end of
input must be reported because no more data will be forwarded. However, it
was performed after receiving the ACK response. It is harmless, but there is
no reason to delay the EOI. It is now fixed.

This patch must be backported to 3.1.

(cherry picked from commit f7e571859629b40defb37ce3d4331a571ba619ec)
Signed-off-by: Willy Tarreau <w@1wt.eu>