ams: centralize system thread definitions

stratosphere/spl/source/spl_main.cpp

@@ -129,6 +129,10 @@ namespace {
 
 int main(int argc, char **argv)
 {
+    /* Set thread name. */
+    os::SetThreadNamePointer(os::GetCurrentThread(), AMS_GET_SYSTEM_THREAD_NAME(spl, Main));
+    AMS_ASSERT(os::GetThreadPriority(os::GetCurrentThread()) == AMS_GET_SYSTEM_THREAD_PRIORITY(spl, Main));
+
     /* Initialize global context. */
     spl::impl::Initialize();