output error when set socket opt fails

common/os_calls.c

@@ -352,6 +352,10 @@ g_tcp_set_no_delay(int sck)
       {
         ret = 0; /* success */
       }
+      else
+      {
+        g_writeln("Error setting tcp_nodelay");
+      }
     }
   }
   else
@@ -389,6 +393,10 @@ g_tcp_set_keepalive(int sck)
       {
         ret = 0; /* success */
       }
+      else
+      {
+        g_writeln("Error setting tcp_keepalive");
+      }
     }
   }
   else