Process events with processEventsWhileBlocked() when blocked.

When we are blocked and a few events a processed from time to time, it
is smarter to call the event handler a few times in order to handle the
accept, read, write, close cycle of a client in a single pass, otherwise
there is too much latency added for clients to receive a reply while the
server is busy in some way (for example during the DB loading).

src/rdb.c

@@ -1073,7 +1073,7 @@ void rdbLoadProgressCallback(rio *r, const void *buf, size_t len) {
         if (server.masterhost && server.repl_state == REDIS_REPL_TRANSFER)
             replicationSendNewlineToMaster();
         loadingProgress(r->processed_bytes);
-        aeProcessEvents(server.el, AE_FILE_EVENTS|AE_DONT_WAIT);
+        processEventsWhileBlocked();
     }
 }