MXS-961: error in replication stream and checksum calculation

When checksum is in use and there is an error in replication stream
master connection the blr_terminate_master_replication has no effect.

MXS-961: The checksum detection calls
blr_master_delayed_connect(router); and connection is scheduled again.

The fix will break the main loop as soon as the error indicator byte is
seen and no other computation will be done (such as checksum)

server/modules/routing/binlog/blr_master.c

@@ -1063,7 +1063,13 @@ blr_handle_binlog_record(ROUTER_INSTANCE *router, GWBUF *pkt)
                 }
                 else
                 {
+                    /* Terminate replication and exit from main loop */
                     blr_terminate_master_replication(router, ptr, len);
+
+                    gwbuf_free(pkt);
+                    pkt = NULL;
+
+                    break;
                 }
 
                 if (hdr.ok == 0)