Merge #11917: Add testnet DNS seed: seed.testnet.bitcoin.sprovoost.nl

f455a24 [net] add seed.testnet.bitcoin.sprovoost.nl to testnet DNS seeds (Sjors Provoost)

Pull request description:

  I tested it myself by:
  * `dig seed.testnet.bitcoin.sprovoost.nl`  (should have propagated by now, but if you only see two records with `A 66.111... ` try again later)
  * deleting the other seeds and all data in `.../testnet3`, recompiling and then starting the node. Log shows `21 addresses found from DNS seeds`.

  ACK https://github.com/bitcoin/bitcoin/blob/master/doc/dnsseed-policy.md

  I'm willing to keep it up and running at least throughout 2018, unless something bad happens.

  About my setup:
  * Amazon EC2 instance in Europe, running Ubuntu 16.04; I use this instance for some other chores, but only port 53 is world reachable (for mainnet I'd probably run a dedicated instance, and perhaps a location I have physical control over)
  * running [sipa/bitcoin-seeder](https://github.com/sipa/bitcoin-seeder) with default settings (and the non-root port redirect)
  * feedback about my domain / DNS setup is welcome, I can provide more details via private email

  I can use guidance on _Any hosting services contracted by the operator are equally expected to uphold these expectations_. Although I assume the requirements for testnet are less strict than for mainnet, in case I want to pursue the latter in the future: what unpleasant things can Amazon, my domain registrar and other intermediaries do? How would I mitigate that?

  Also note that The Netherlands passed some pretty onerous legislation creating uncertainty over what the secret service can compel people like myself to do. However these laws won't take effect before mid 2018, there's probably more interesting targets than myself to go after, and it's easier for them to just monitor all unencrypted P2P traffic everywhere, or monitor some intermediary I depend on.

  Any good tools for monitoring uptime?

Tree-SHA512: 386fe688e5006ab8352d93ab3954fc07dc566876ae002891baa51acfaa5bb113f51b1f5ca08c7394a530b10a2f5008c56d57153af3ed07544a305586dda06b97

src/chainparams.cpp

@@ -231,6 +231,7 @@ public:
         // nodes with support for servicebits filtering should be at the top
         vSeeds.emplace_back("testnet-seed.bitcoin.jonasschnelli.ch", true);
         vSeeds.emplace_back("seed.tbtc.petertodd.org", true);
+        vSeeds.emplace_back("seed.testnet.bitcoin.sprovoost.nl", true);
         vSeeds.emplace_back("testnet-seed.bluematt.me", false);
 
         base58Prefixes[PUBKEY_ADDRESS] = std::vector<unsigned char>(1,111);