[STATS] report HTTP requests (total and rate) in frontends

Now that we support keep-alive, it's important to report a separate
counter for requests. Right now it just appears in the CSV output.
diff --git a/include/types/proxy.h b/include/types/proxy.h
index fabc936..53c00f7 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -225,6 +225,7 @@
 	int nbpend;				/* number of pending connections with no server assigned yet */
 	int totpend;				/* total number of pending connections on this instance (for stats) */
 	unsigned int feconn, beconn;		/* # of active frontend and backends sessions */
+	struct freq_ctr fe_req_per_sec;		/* HTTP requests per second on the frontend */
 	struct freq_ctr fe_sess_per_sec;	/* sessions per second on the frontend */
 	struct freq_ctr be_sess_per_sec;	/* sessions per second on the backend */
 	unsigned int maxconn;			/* max # of active sessions on the frontend */