[Client] With -N, print nb of remaining trx

When the -N option is used, the number of remaining request
transmissions is printed after each transmission.

owlps-client/owlps-client.c

@@ -166,6 +166,10 @@ int main(int argc, char *argv[])
       uint_fast32_t trx_time, sleep_time ;
       owl_timestamp now ;
 
+      if (options.verbose && options.nb_requests)
+        printf("%"PRIuFAST16" more requests to transmit.\n",
+               nb_requests_left) ;
+
       if (options.add_flood_delay)
         owl_msleep(options.flood_delay) ;
       else