Partial fix to #463, http://bugs.skysql.com/show_bug.cgi?id=463

log_manager.cc: fixed block buffer overflow. Queries are logged to trace log and long queries exceed the bufsize in length. Those were written beyond allocated memory areas.
mysql_client_server_protocol.h: added mysql_protocol_state_t to indicate whether MySQL protocol object is allocated, usable or freed. Freed means that memory allocations made by the protocol are freed. That is, command history etc.
mysql_backend.c: gw_backend_hangup and gw_error_backend_event used to call error handling function although session was already closing. Added check for session state.
mysql_client.c: route_by_statement lost some packets in case where query was sent in multiple packets.
mysql_common.c: gw_MySQL_get_next_packet failed in packet handling with route_by_statement. When multi-packet query was merged into one, packet type wasn't copied.
	protocol_archive_srv_command and mysql_protocol_done didn't have proper locking in place which lead to occasional crashes.

server/include/dcb.h

@@ -145,9 +145,9 @@ typedef enum {
         DCB_STATE_POLLING,      /*< Waiting in the poll loop */
         DCB_STATE_LISTENING,    /*< The DCB is for a listening socket */
         DCB_STATE_DISCONNECTED, /*< The socket is now closed */
-        DCB_STATE_FREED,        /*< Memory freed */
         DCB_STATE_NOPOLLING,    /*< Removed from poll mask */
-        DCB_STATE_ZOMBIE        /*< DCB is no longer active, waiting to free it */
+        DCB_STATE_ZOMBIE,       /*< DCB is no longer active, waiting to free it */
+        DCB_STATE_FREED         /*< Memory freed */
 } dcb_state_t;
 
 typedef enum {