Add a "fork" of musl as //fusl.

fusl/include/sys/msg.h

+#ifndef _SYS_MSG_H
+#define _SYS_MSG_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <sys/ipc.h>
+
+#define __NEED_pid_t
+#define __NEED_key_t
+#define __NEED_time_t
+#define __NEED_size_t
+#define __NEED_ssize_t
+
+#include <bits/alltypes.h>
+
+typedef unsigned long msgqnum_t;
+typedef unsigned long msglen_t;
+
+#include <bits/msg.h>
+
+#define __msg_cbytes msg_cbytes
+
+#define MSG_NOERROR 010000
+#define MSG_EXCEPT  020000
+
+#define MSG_STAT 11
+#define MSG_INFO 12
+
+struct msginfo {
+        int msgpool, msgmap, msgmax, msgmnb, msgmni, msgssz, msgtql;
+        unsigned short msgseg;
+};
+
+int msgctl (int, int, struct msqid_ds *);
+int msgget (key_t, int);
+ssize_t msgrcv (int, void *, size_t, long, int);
+int msgsnd (int, const void *, size_t, int);
+
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+struct msgbuf {
+        long mtype;
+        char mtext[1];
+};
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif