Large events are now processed in chuncks

The router->last_written is used to store the position where the last event was
written. The replication header is also stored in a separate structure in
the router which is used later when the last packet of a multi-packet event
arrives.

server/modules/include/mysql_client_server_protocol.h

@@ -80,6 +80,9 @@
 #define GW_MYSQL_SCRAMBLE_SIZE 20
 #define GW_SCRAMBLE_LENGTH_323 8
 
+/** Maximum length of a MySQL packet */
+#define MYSQL_PACKET_LENGTH_MAX 0x00ffffff
+
 #ifndef MYSQL_SCRAMBLE_LEN
 # define MYSQL_SCRAMBLE_LEN GW_MYSQL_SCRAMBLE_SIZE
 #endif