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

fusl/src/stat/futimesat.c

+#define _GNU_SOURCE
+#include <sys/time.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include "syscall.h"
+#include "libc.h"
+
+int __futimesat(int dirfd, const char *pathname, const struct timeval times[2])
+{
+        struct timespec ts[2];
+        if (times) {
+                int i;
+                for (i=0; i<2; i++) {
+                        if (times[i].tv_usec >= 1000000ULL)
+                                return __syscall_ret(-EINVAL);
+                        ts[i].tv_sec = times[i].tv_sec;
+                        ts[i].tv_nsec = times[i].tv_usec * 1000;
+                }
+        }
+        return utimensat(dirfd, pathname, times ? ts : 0, 0);
+}
+
+weak_alias(__futimesat, futimesat);