telnet: Flush the console after every character

Make sure that every character is written to the stdout. This
way typing 'help' will always flush everything.
diff --git a/util/telnet-client.c b/util/telnet-client.c
index d8346e4..6e17726 100644
--- a/util/telnet-client.c
+++ b/util/telnet-client.c
@@ -94,6 +94,7 @@
 	/* data received */
 	case TELNET_EV_DATA:
 		printf("%.*s", (int)ev->size, ev->buffer);
+		fflush(stdout);
 		break;
 	/* data must be sent */
 	case TELNET_EV_SEND: