MINOR: spoe: Don't stop disabled proxies

SPOE register a signal handler to be able to stop SPOE applets ASAP during
soft-stop. Disabled proxies must be ignored at this staged because they are
not fully configured.

For now, it is useless but this change is mandatory to fix a bug.
diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index 6ab1cfb..301d950 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -2987,6 +2987,14 @@
 	while (p) {
 		struct flt_conf *fconf;
 
+		/* SPOE filter are not initialized for disabled proxoes. Move to
+		 * the next one
+		 */
+		if (p->flags & PR_FL_DISABLED) {
+			p = p->next;
+			continue;
+		}
+
 		list_for_each_entry(fconf, &p->filter_configs, list) {
 			struct spoe_config *conf;
 			struct spoe_agent  *agent;