MINOR: spoe: Add a pointer on the filter config in the spoe_agent structure

There was no way to access the SPOE filter configuration from the agent
object. However it could be handy to have it. And in fact, this will be
required to fix a bug.

(cherry picked from commit 434b8525ee333f511b5461eae41b23842d3636d4)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index a68f7b9..8042312 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -4413,6 +4413,7 @@
 
 	conf->id    = strdup(engine ? engine : curagent->id);
 	conf->agent = curagent;
+	curagent->spoe_conf = conf;
 
 	/* Start agent's proxy initialization here. It will be finished during
 	 * the filter init. */