Remove ucore_ prefix from headers and source files

test/test_threadqueue.c

@@ -3,7 +3,7 @@
 #include <errno.h>
 #include <sched.h>
 #include <stdlib.h>
-#include <ucore/ucore_threadqueue.h>
+#include <ucore/threadqueue.h>
 
 struct thr_msg {
     struct uc_threadmsg msg;