BUG/MINOR: spoe: Fix soft stop handler using a specific id for spoe filters

During a soft stop, we need to wakeup all SPOE applets to stop them. So we loop
on all proxies, and for each proxy, on all filters. But we must be sure to only
handle SPOE filters here. To do so, we use a specific id.
diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index 519d6bb..88f782f 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -235,6 +235,9 @@
 	unsigned int        process_exp;  /* expiration date to process an event */
 };
 
+/* SPOE filter id. Used to identify SPOE filters */
+const char *spoe_filter_id = "SPOE filter";
+
 /* Set if the handle on SIGUSR1 is registered */
 static int sighandler_registered = 0;
 
@@ -2282,10 +2285,16 @@
 		struct flt_conf *fconf;
 
 		list_for_each_entry(fconf, &p->filter_configs, list) {
-			struct spoe_config *conf  = fconf->conf;
-			struct spoe_agent  *agent = conf->agent;
+			struct spoe_config *conf;
+			struct spoe_agent  *agent;
 			struct appctx      *appctx;
 
+			if (fconf->id != spoe_filter_id)
+				continue;
+
+			conf  = fconf->conf;
+			agent = conf->agent;
+
 			list_for_each_entry(appctx, &agent->cache, ctx.spoe.list) {
 				si_applet_want_get(appctx->owner);
 				si_applet_want_put(appctx->owner);
@@ -3159,6 +3168,7 @@
 	}
 
 	*cur_arg    = pos;
+	fconf->id   = spoe_filter_id;
 	fconf->ops  = &spoe_ops;
 	fconf->conf = conf;
 	return 0;