RandomX fixes

Intel JCC erratum fix and various other improvements, see more here: https://www.phoronix.com/scan.php?page=article&item=intel-jcc-microcode&num=1

src/App.cpp

@@ -33,6 +33,7 @@
 #include "base/io/Console.h"
 #include "base/io/log/Log.h"
 #include "base/kernel/Signals.h"
+#include "base/kernel/Platform.h"
 #include "core/config/Config.h"
 #include "core/Controller.h"
 #include "core/Miner.h"
@@ -89,6 +90,8 @@ int xmrig::App::exec()
 
     m_controller->start();
 
+    Platform::setThreadPriority(5);
+
     rc = uv_run(uv_default_loop(), UV_RUN_DEFAULT);
     uv_loop_close(uv_default_loop());