Merge #11962: [net] add seed.bitcoin.sprovoost.nl to DNS seeds

ffcc687 [net] add seed.bitcoin.sprovoost.nl to DNS seeds (Sjors Provoost)

Pull request description:

  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.

  Same setup as #11917, but with a dedicated instance.

Tree-SHA512: df0c8ab705628b8da4d0a0cb753759a699a6a91907a76e13c08cbdbeae81131af0f6040183dab7f00851e0c57dcd91f5cd5ce43482d1f13432a58c8943692e90

src/chainparams.cpp

@@ -135,6 +135,7 @@ class CMainParams : public CChainParams {
         vSeeds.emplace_back("seed.bitcoinstats.com"); // Christian Decker, supports x1 - xf
         vSeeds.emplace_back("seed.bitcoin.jonasschnelli.ch"); // Jonas Schnelli, only supports x1, x5, x9, and xd
         vSeeds.emplace_back("seed.btc.petertodd.org"); // Peter Todd, only supports x1, x5, x9, and xd
+        vSeeds.emplace_back("seed.bitcoin.sprovoost.nl"); // Sjors Provoost
 
         base58Prefixes[PUBKEY_ADDRESS] = std::vector<unsigned char>(1,0);
         base58Prefixes[SCRIPT_ADDRESS] = std::vector<unsigned char>(1,5);