www.opendns.com can take more than 5 sec to load, so check connectivity

with guide.opendns.com instead.

DNSCrypt-Preference-Pane/DNSCrypt/extra/usr/scripts/check-hijacking.sh

@@ -8,7 +8,8 @@ try_resolution() {
 }
 
 try_http_query() {
-  exec alarmer 5 curl -m 5 http://www.opendns.com 2>/dev/null | \
+  exec alarmer 5 curl -L --max-redirs 5 -4 -m 5 \
+    http://guide.opendns.com/main 2>/dev/null | \
   fgrep -ic OpenDNS > /dev/null 2>&1
 }