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

fusl/src/ipc/semctl.c

+#include <sys/sem.h>
+#include <stdarg.h>
+#include "syscall.h"
+#include "ipc.h"
+
+union semun {
+        int val;
+        struct semid_ds *buf;
+        unsigned short *array;
+};
+
+int semctl(int id, int num, int cmd, ...)
+{
+        union semun arg = {0};
+        va_list ap;
+        switch (cmd) {
+        case SETVAL: case GETALL: case SETALL: case IPC_STAT: case IPC_SET:
+        case IPC_INFO: case SEM_INFO: case SEM_STAT:
+                va_start(ap, cmd);
+                arg = va_arg(ap, union semun);
+                va_end(ap);
+        }
+#ifdef SYS_semctl
+        return syscall(SYS_semctl, id, num, cmd | IPC_64, arg.buf);
+#else
+        return syscall(SYS_ipc, IPCOP_semctl, id, num, cmd | IPC_64, &arg.buf);
+#endif
+}