Close binlogrouter connections in thread 0

The internal connections of the binlogrouter should be closed in the same
thread that created them. This should be the "main" thread, i.e. thread 0,
that starts the original binlogrouter service.

server/modules/routing/binlogrouter/blr.c

@@ -1137,7 +1137,7 @@ createInstance(SERVICE *service, char **options)
         }
 
         /* Start replication from master server */
-        blr_start_master(inst);
+        blr_start_master_in_main(inst);
     }
 
     return (MXS_ROUTER *)inst;