MINOR: Add ModSecurity wrapper as contrib

This patch contains a base for a modsecurity wrapper in HAProxy using SPOE.
diff --git a/contrib/modsecurity/spoa.h b/contrib/modsecurity/spoa.h
new file mode 100644
index 0000000..daee6d2
--- /dev/null
+++ b/contrib/modsecurity/spoa.h
@@ -0,0 +1,53 @@
+/*
+ * Modsecurity wrapper for haproxy
+ *
+ * This file contains the headers of the bootstrap for laucnching and scheduling
+ * modsecurity for working with HAProxy SPOE protocol.
+ *
+ * Copyright 2016 OZON, Thierry Fournier <thierry.fournier@ozon.io>
+ *
+ * This file is inherited from "A Random IP reputation service acting as a Stream
+ * Processing Offload Agent"
+ *
+ * Copyright 2016 HAProxy Technologies, Christopher Faulet <cfaulet@haproxy.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+#ifndef __SPOA_H__
+#define __SPOA_H__
+
+#include <event2/util.h>
+#include <event2/event.h>
+#include <event2/event_struct.h>
+#include <event2/thread.h>
+
+struct worker {
+	pthread_t           thread;
+	int                 id;
+	struct event_base  *base;
+	struct event       *monitor_event;
+
+	struct list         engines;
+
+	unsigned int        nbclients;
+	struct list         clients;
+
+	struct list         frames;
+};
+
+#define LOG(worker, fmt, args...)                                       \
+	do {								\
+		struct timeval  now;					\
+                                                                        \
+		gettimeofday(&now, NULL);				\
+		fprintf(stderr, "%ld.%06ld [%02d] " fmt "\n",		\
+			now.tv_sec, now.tv_usec, (worker)->id, ##args);	\
+	} while (0)
+
+#endif /* __SPOA_H__ */
+
+extern struct worker null_worker;