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

fusl/include/sys/select.h

+#ifndef _SYS_SELECT_H
+#define _SYS_SELECT_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <features.h>
+
+#define __NEED_size_t
+#define __NEED_time_t
+#define __NEED_suseconds_t
+#define __NEED_struct_timeval
+#define __NEED_struct_timespec
+#define __NEED_sigset_t
+
+#include <bits/alltypes.h>
+
+#define FD_SETSIZE 1024
+
+typedef unsigned long fd_mask;
+
+typedef struct
+{
+        unsigned long fds_bits[FD_SETSIZE / 8 / sizeof(long)];
+} fd_set;
+
+#define FD_ZERO(s) do { int __i; unsigned long *__b=(s)->fds_bits; for(__i=sizeof (fd_set)/sizeof (long); __i; __i--) *__b++=0; } while(0)
+#define FD_SET(d, s)   ((s)->fds_bits[(d)/(8*sizeof(long))] |= (1UL<<((d)%(8*sizeof(long)))))
+#define FD_CLR(d, s)   ((s)->fds_bits[(d)/(8*sizeof(long))] &= ~(1UL<<((d)%(8*sizeof(long)))))
+#define FD_ISSET(d, s) !!((s)->fds_bits[(d)/(8*sizeof(long))] & (1UL<<((d)%(8*sizeof(long)))))
+
+int select (int, fd_set *__restrict, fd_set *__restrict, fd_set *__restrict, struct timeval *__restrict);
+int pselect (int, fd_set *__restrict, fd_set *__restrict, fd_set *__restrict, const struct timespec *__restrict, const sigset_t *__restrict);
+
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+#define NFDBITS (8*(int)sizeof(long))
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+#endif