添加musl libc.

mkrtos_user/lib/sys/inc/u_prot.h

@@ -1,3 +1,29 @@
 #pragma once
 
-#include <stdint.h>
+#include "u_types.h"
+
+#define FACTORY_PROT 1
+#define THREAD_PROT 2
+#define TASK_PROT 3
+#define LOG_PROT 4
+#define IPC_PROT 5
+
+typedef struct msg_tag
+{
+    union
+    {
+        umword_t raw;
+        struct
+        {
+            umword_t type : 4;
+            umword_t type2 : 8;
+            umword_t prot : (sizeof(umword_t) * 8) - 12;
+        };
+    };
+} msg_tag_t;
+
+#define msg_tag_init(r) \
+    ((msg_tag_t){.raw = (r)})
+
+#define msg_tag_init3(t, t2, p) \
+    msg_tag_init(((umword_t)(t)&0xf) | (((umword_t)(t2)&0xff) << 4) | (((umword_t)(p)) << 12))