MEDIUM: log: Use linked lists for loggers

This patch settles the 2 loggers limitation.
Loggers are now stored in linked lists.

Using "global log", the global loggers list content is added at the end
of the current proxy list. Each "log" entries are added at the end of
the proxy list.

"no log" flush a logger list.
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 2abd213..593260e 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -283,10 +283,7 @@
 	char *iface_name;			/* bind interface name or NULL */
 	int (*accept)(struct session *s);       /* application layer's accept() */
 	struct proxy *next;
-	struct logsrv logsrv1, logsrv2;		/* 2 syslog servers */
-	signed char logfac1, logfac2;		/* log facility for both servers. -1 = disabled */
-	int loglev1, loglev2;			/* log level for each server, 7 by default */
-	int minlvl1, minlvl2;			/* minimum log level for each server, 0 by default */
+	struct list logsrvs;
 	int to_log;				/* things to be logged (LW_*) */
 	int stop_time;                          /* date to stop listening, when stopping != 0 (int ticks) */
 	struct hdr_exp *req_exp;		/* regular expressions for request headers */