Update creating thread to yield if the new thread has higher priority

src/threads/thread.c

@@ -223,6 +223,10 @@ thread_create (const char *name, int priority,
   /* Add to run queue. */
   thread_unblock (t);
 
+  /* Yield if the new thread has a higher priority than the current thread. */
+  if (priority > thread_get_priority ())
+    thread_yield ();
+
   return tid;
 }