Remove ChainParams::DefaultMinerThreads

No longer relevant after #5957. This hack existed because of another
hack where the numthreads parameter, on regtest, doubled as how many
blocks to generate.

src/chainparams.cpp

@@ -59,7 +59,6 @@ public:
         pchMessageStart[3] = 0x64;
         vAlertPubKey = ParseHex("04b7ecf0baa90495ceb4e4090f6b2fd37eec1e9c85fac68a487f3ce11589692e4a317479316ee814e066638e1db54e37a10689b70286e6315b1087b6615d179264");
         nDefaultPort = 8233;
-        nMinerThreads = 0;
         nMaxTipAge = 24 * 60 * 60;
         nPruneAfterHeight = 100000;
         const size_t N = 200, K = 9;
@@ -219,7 +218,6 @@ public:
         pchMessageStart[3] = 0xbf;
         vAlertPubKey = ParseHex("044e7a1553392325c871c5ace5d6ad73501c66f4c185d6b0453cf45dec5a1322e705c672ac1a27ef7cdaf588c10effdf50ed5f95f85f2f54a5f6159fca394ed0c6");
         nDefaultPort = 18233;
-        nMinerThreads = 0;
         nPruneAfterHeight = 1000;
 
         //! Modify the testnet genesis block so the timestamp is valid for a later start.
@@ -308,7 +306,6 @@ public:
         pchMessageStart[1] = 0xe8;
         pchMessageStart[2] = 0x3f;
         pchMessageStart[3] = 0x5f;
-        nMinerThreads = 1;
         nMaxTipAge = 24 * 60 * 60;
         const size_t N = 48, K = 5;
         BOOST_STATIC_ASSERT(equihash_parameters_acceptable(N, K));

src/chainparams.h

@@ -53,8 +53,6 @@ public:
     const std::vector<unsigned char>& AlertKey() const { return vAlertPubKey; }
     int GetDefaultPort() const { return nDefaultPort; }
 
-    /** Used if GenerateBitcoins is called with a negative number of threads */
-    int DefaultMinerThreads() const { return nMinerThreads; }
     const CBlock& GenesisBlock() const { return genesis; }
     /** Make miner wait to have peers to avoid wasting work */
     bool MiningRequiresPeers() const { return fMiningRequiresPeers; }
@@ -91,7 +89,6 @@ protected:
     //! Raw pub key bytes for the broadcast alert signing key.
     std::vector<unsigned char> vAlertPubKey;
     int nDefaultPort = 0;
-    int nMinerThreads = 0;
     long nMaxTipAge = 0;
     uint64_t nPruneAfterHeight = 0;
     unsigned int nEquihashN = 0;

src/miner.cpp

@@ -748,13 +748,8 @@ void GenerateBitcoins(bool fGenerate, int nThreads)
 {
     static boost::thread_group* minerThreads = NULL;
 
-    if (nThreads < 0) {
-        // In regtest threads defaults to 1
-        if (Params().DefaultMinerThreads())
-            nThreads = Params().DefaultMinerThreads();
-        else
-            nThreads = GetNumCores();
-    }
+    if (nThreads < 0)
+        nThreads = GetNumCores();
 
     if (minerThreads != NULL)
     {