tcp_rexmit(): no need to call tcp_output, since always called from tcp_input and thus tcp_output always returns without sending (prevent confusion by thinking data was sent while in tcp_rexmit!)

src/core/tcp_out.c

@@ -864,7 +864,8 @@ tcp_rexmit(struct tcp_pcb *pcb)
 
   /* Do the actual retransmission. */
   snmp_inc_tcpretranssegs();
-  tcp_output(pcb);
+  /* No need to call tcp_output: we are always called from tcp_input()
+     and thus tcp_output directly returns. */
 }