PowerPC: Set host CPU rounding mode on init and savestate

Not doing this can cause desyncs when TASing. (I don't know
how common such desyncs would be, though. For games that
don't change rounding modes, they shouldn't be a problem.)

Source/Core/Core/Core.cpp

@@ -25,6 +25,7 @@
 #include "Common/CommonPaths.h"
 #include "Common/CommonTypes.h"
 #include "Common/Event.h"
+#include "Common/FPURoundMode.h"
 #include "Common/FileUtil.h"
 #include "Common/Flag.h"
 #include "Common/Logging/Log.h"
@@ -625,6 +626,7 @@ static void EmuThread(std::unique_ptr<BootParameters> boot, WindowSystemInfo wsi
     // thread, and then takes over and becomes the video thread
     Common::SetCurrentThreadName("Video thread");
     UndeclareAsCPUThread();
+    FPURoundMode::LoadDefaultSIMDState();
 
     // Spawn the CPU thread. The CPU thread will signal the event that boot is complete.
     s_cpu_thread = std::thread(cpuThreadFunc, savestate_path, delete_savestate);