Convert total timeout to per-query (#467)

On Apple platforms, libresolv reports the total timeout in retrans, not the per-query time. This patch undoes that math to get the per-query time, which is what c-ares expects. This is not perfect because libresolv is inconsistent on whether the timeout is multiplied by retry or retry+1, but I don't see any way to distinguish these cases.

Fix By: Marc Aldorasi (@marc-groundctl)

src/lib/ares_init.c

@@ -1347,8 +1347,12 @@ static int init_by_resolv_conf(ares_channel channel)
       channel->tries = res.retry;
     if (channel->rotate == -1)
       channel->rotate = res.options & RES_ROTATE;
-    if (channel->timeout == -1)
+    if (channel->timeout == -1) {
       channel->timeout = res.retrans * 1000;
+#ifdef __APPLE__
+      channel->timeout /= (res.retry + 1) * (res.nscount > 0 ? res.nscount : 1);
+#endif
+    }
 
     res_ndestroy(&res);
   }