Auto merge of #2227 - str4d:2074-ignore-virtual-cores, r=str4d

Use real number of cores, ignore virtual cores

Cherry-picked from the following upstream PRs:

- bitcoin/bitcoin#6361
- bitcoin/bitcoin#6370

Part of #2074.

src/init.cpp

@@ -351,7 +351,7 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-loadblock=<file>", _("Imports blocks from external blk000??.dat file") + " " + _("on startup"));
     strUsage += HelpMessageOpt("-maxorphantx=<n>", strprintf(_("Keep at most <n> unconnectable transactions in memory (default: %u)"), DEFAULT_MAX_ORPHAN_TRANSACTIONS));
     strUsage += HelpMessageOpt("-par=<n>", strprintf(_("Set the number of script verification threads (%u to %d, 0 = auto, <0 = leave that many cores free, default: %d)"),
-        -(int)boost::thread::hardware_concurrency(), MAX_SCRIPTCHECK_THREADS, DEFAULT_SCRIPTCHECK_THREADS));
+        -GetNumCores(), MAX_SCRIPTCHECK_THREADS, DEFAULT_SCRIPTCHECK_THREADS));
 #ifndef WIN32
     strUsage += HelpMessageOpt("-pid=<file>", strprintf(_("Specify pid file (default: %s)"), "zcashd.pid"));
 #endif
@@ -927,7 +927,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     // -par=0 means autodetect, but nScriptCheckThreads==0 means no concurrency
     nScriptCheckThreads = GetArg("-par", DEFAULT_SCRIPTCHECK_THREADS);
     if (nScriptCheckThreads <= 0)
-        nScriptCheckThreads += boost::thread::hardware_concurrency();
+        nScriptCheckThreads += GetNumCores();
     if (nScriptCheckThreads <= 1)
         nScriptCheckThreads = 0;
     else if (nScriptCheckThreads > MAX_SCRIPTCHECK_THREADS)